Why Change the Oil in Your Motor?

Note to self: Do not purchase an automobile previously owned by ciro.

How do you feel about changing the oil filter? More propoganda?

You don't absolutely have to change the oil in your motor.

I know a young lady in Arizona who drove her car over 100,000 miles, all in Arizona, and never changed oil or filter. She checked and refilled it often enough to keep oil in it.

I change mine because I thik it's cheap insurance. I have 160,000 easy miles on my pickup and it's still like new. Would it be in the same shape if I had not changed the oil, I don't know. Maybe, when I've got about 300,000 miles, I'll quit changing the oil and see how long it'll keep going.

The motor NEEDS lubrication. The motor may be able to tolerante poorer quality lubricants that have been neither changed nor filtered.

Engine Oil provides a cleaning and lubricating function in your engine.

Over time the oil breaks down and the effectiveness of these functions reduces.

Old Oil runs hotter and thickens over time and may start to block or reduce the flow through some of the smaller Chambers in the block.

Have you noticed that the oil goes Black???
That's Dirt and Carbon that is being carried around the engine that the filter can't remove because it is too small, but it will still add wear & tear and reduce the life of your engine.

Synthetic Oils last longer, but I would still stick with the engine manufacturer Specs.

Engine manufacturers specify oil and filter change periods for a reason...to make their engines run better for longer to make them look good in the market place and so you don't have to go back & complain about you vehicle breaking down all the time.

Me...I just go with the manufacturers specs give or take, but never too far beyond the mileage that are specified (+/- 2000kms).

Regards.
Sapper

The argument you mention sounds to me very familiar from the commercial side but to believe is needed more technical explanation

Some questions arises

Which combustion products contaminate the oil: carbon, hydrogen, oxygen, co2, h2O ?

How is the process for the acidification of the oil? which acid is produced

All small metal will go down to the bottom of the motor or filtered, the smallest particles are carbon (graphites) that is also a lubricating material.

Which combustion products contaminate the oil: carbon, hydrogen, oxygen, co2, h2O ?

It's really not that simple. You may be getting carbon deposition that can find its way into the oil, unburnt fuel washing in & diluting the oil: partially combusted & polymerized hydrocarbons as well as CO2 & H2O, sulphur & nitrogen compounds are all formed during the combustion process- this is the reason for catalytic converters!!!-& some will find it's way past the rings. Even though they may be gaseous, these compounds do also absorb into the oil.

How is the process for the acidification of the oil? which acid is produced

Anything that goes into acid rain (from blowby); the predominant process would likely be oxidation of the oil to carboxylate compounds of far more types than I'd dream of trying to list.

All small metal will go down to the bottom of the motor or filtered, the smallest particles are carbon (graphites) that is also a lubricating material.

You hope!! All modern automotive engines rely on splash lubrication to a certain extent: they have this neat thingumy called a crankshaft whirling around, oil being pumped in & out-NOT a static envoronment for nice sedimenting! These particles will all go through the oil pump & wear on it, then help plug up the filter. although if you never change the oil, the varnish buildup on the bottom of the pan might help hold it down in nice fossilized layers...

The acid is sulfuric acid and forms with the combination of water and the sulfur in the oil.

The sludge is a mix of combustion (carbon, soot, oxidation of the oil, and probably eye of newt for all I know).

I guess it is it is one thing to academically want to know the details, but foolish to challenge tribal knowledge with a high risk outcome.

If you really are stubbornly set against the idea that oil needs to be changed, then I suggest you not change your oil and wait for engine failure. See how far it goes. Then repeat with a new engine again and again. Then analyze your data and write up a conclusion. Report back and settle the argument.

I think it is an expensive way to get an education, but maybe you can qualify for a student loan?

Dear Relativity PL:

To get the carbon cristalization you need peassures in the order of 5GPa and temperatures 1500C° conditions that you will never get in a motor so all the carbon in the oil is amorphous and i don´t think that the carbon in the oil will be abrasive, in fact i read that the amorfhous carbon (Graphites) is used an additive in some types of grease and lubricant oil as you probably know.

I recognize the sulfuric acid may be a problem but i think it is produced in a very small scale due to the small sulphur contamination present in the modern gasoline and oil.

Any way, from all this i am thinking that will be a good idea to add an oil PH meter in the control pannel in the car so you can see when there is a need to change the oil or just add as an additive to compensate the acidity.

Some corrections

Dear Relativity PL:

To get the carbon cristalization you need peassures in the order of 5GPa and temperatures 1500C° conditions that you will never get in a motor so all the carbon in the oil is amorphous and i don´t think that the carbon in the oil will be abrasive, in fact i read that the amorphous carbon (Graphites) is used as an additive in some types of grease and lubricant oil as you probably know.

I recognize the sulfuric acid may be a problem but i think it is produced in a very small scale due to the small sulphur contamination present in the modern gasoline and oil.

Any way, from all this i am thinking that will be a good idea to add an oil PH meter in the control pannel in the car so you can see when there is a need to change the oil or just add an additive to compensate the acidity.

I'm glad you're confident that only steel-industry temperatures and pressures create coke. Millions of auto owners would disagree with you:

http://www.torquecars.com/forums/threads/when-do-you-need-to-decoke-an-engine.19973/

Good answer. I'd add another item to your list if I may, unburned gasoline (incomplete combustion dues to numerous mechanical/electrical problems) dilutes the oil.

I save time by mixing soot into any new engine oil I buy.
I find the abrasive properties help the engine to bed in quickly.
Uriating into the 710 hole and gas tank also helps peformance.
Del
(On a more serious note. I'd say the stupidly frequent sparkplug changes are more of a con trick. The planet will soon be knee deep in perfectly good, slightly used spark plugs...)

<...Urinating into the 710 hole and gas tank also helps peformance....>

OUCH!!! Did you shut the engine off first?

I thought I was only s'posed to put urea into my diesel engine! Dang! Thanks for the tip!

My aunt drove a 1967 Bel Air for the better part of 120k miles. She changed her oil on a very erratic schedule, sometimes letting 10k miles pass before having it changed. It threw a rod while she was on a trip down I-95.

My brothers & I were the recipients of the carcass. Twas fun digging into the car to see what made it tick (or didn't as the case was). We pulled the engine and dissected it. Indeed the part of the connecting rod that was still attached to the crankshaft had poked a neat hole in the side of the block!

The most relevant thing about this story is the inch thick layer of sludge that had caked onto the crankcase walls. This is the primary reason I won't let my car go more than 5k miles without an oil change.

The most catastrophic engine failure I have seen was my late 60's VW Bug.

Was driving to the doctor's in the middle of a bad snow storm when the car just stalled.

A few minutes went by and someone drove up behind me and offered a push to start it, "These things usually start when you give them a push." "Good idea," I thankfully replied.

Sure enough, it roared to life, but was running rough. Still, I was on my way...

About a mile later it stalled again and I was stranded. Then another car came up from behind and asked if I needed a push. "These things usually start when you give them a push," I yelled back. Once again it roared to life and I limped to the doctor's office.

While the doctor was examining my son I went back out and popped the engine lid and tried to see where the trouble was...

This was one of those things where the obvious just smacks you numb in the face and you still can't get it. I stared at the engine thinking, "Something looks different, but what?"

After a few more seconds I recognized what I was looking at... Both driver's side cylinder heads were missing (as in gone) and all I saw was two jagged remains of connecting rods hanging out the side of what was left of the block.

All the oil was gone, but when it cooled down it would run on the two remaining cylinders until the engine got too hot and it would seize. Let it cool back down and it would run once again.

See? No need to change the oil. Either:

• Change the cylinder heads, or
• Let it cool down.

Sheesh!

You've got to hand it to German engineering! Two cylinders gone!? ...and it still 'ran'.

You think that ones good my wife sold her Toyota Tercelle to a deaf friend we told her not to get on the highway since it had a wrist pin knocking. You guessed it first thing she did was go to Tennessee. Guess what, I get the call to go get the car three states away, when I get there she says the car is making a funny noise I open the hood and I look inside the crankcase and watch the rods spinning around on the crankshaft but alas it was still running and she wanted her money back for her mistake. BUT IT WAS STILL RUNNING ON TWO CYLINDERS. That would only happen to the clueless in life, me it would just lock up. on a side note if you look at the carbon under a microscope the carbon that is created under combustion is not a smooth type of carbon it is very jagged and extremely abrasive and not very pretty to look at when you see the damage it does. After we have run our motors on the dyno for an extended period of time we change the oil, just to be safe. And lo and behold what do we find but the fresh oil makes more horsepower. When we restart the engine for a second pull the fresh oil was worth almost 12 HP. On synthetic oil on conventional oil it increased only about 6-7 HP. I would say changing your oil is one of the most critical things you do for your transport. Until Scotty can beam us to some exotic place I suggest you change your oil unless you want a very expensive piece of yard artDuke

All very good reasons but have missed what the primary purpose of a lubricant is.

A lubricant is applied to moving parts to prevent metal to contact of those parts. Typically this 'lubricant film' is bewteen 2 & 3 microns thick and is under enormous pressure during normal running. This prevents the huge amount of friction that would otherwise occur with the film.

During normal running contaminants are invariably introduced into the system through breathers, air filters etc. By contaminant i mean anything larger than 3 microns which, by the way, is about half the size of a human red blood cell. If this is introduced into the film the pressure increases exponentially and causes rapid gear and bearing failures. Water contamination can do the same thing.

The writers above refer mostly to lubricant deterioration which in turns changes the viscosity of the oil which in turn impacts the film thickness. Too much film increases the pressure, too little film means the metal is coming into contact.

Also do not discount the contamination caused by combustion.

So your choice, there are plenty of reasons to change your oil. Let's face it how much does it cost to change oil at frequent intervals. Takes about half an hour to do it yourself.

Personnally I think the original question was raised by someone who is just plain cheap and doesn't want to spend money.

It is probably a split between preventing metal-to-metal contact and scavenging heat away from the components.

In my Bug's case the seizing was caused by expansion of metal due to heat. Yes, the cylinder walls will get scored, but the inability to wick heat away is a critical function.

Examples of this is with the 1970s and 1980s Porsche 911 engines where insufficient oil cooling of the valve stems lead to catastrophic valve failures if left unchecked.

The VW Bug engines and the 911 "Boxer" engines are often called air cooled engines, but that is not really true - they are oil cooled engines. The 911 6-cylinder engines typically used 10 to 12 quarts of oil with an auxiliary oil sump and oil cooler.

Yes the 911 had a remote oil reservoir, about 2-3 quarts in the engine and 6-7 quarts in the remote oil reservoir.

On a side note on the 911, on of the problems I have come across when I was at my 911 mechanic. I would see a late model 911 with the engine blown.

People that would change the oil themselves (usually to save $) would not take precautions and care. Crap would drop into the fill tube, problem with this is that on the 911's air cooled ........ it would first pump the oil through the engine, and on the return then go then through the filter.........guess what the crap that dropped in did?

Wow, what a testimonial to the Volkswagon H4 engine!

Did all the coolant leak out as well?

Great story!

In my college days (in the late 60's and early 70's) I worked as a VW and Porsche mechanic. Interstate 80 was close by. Each year we'd have several destroyed engines as a result of people with the same story: "The oil pressure light came on, but the car was running fine, so I pressed on."

Some of these engines had most of what would otherwise move (piston shards, con rod pieces, etc.) lying in the bottom of what was left of the crankcase. The cylinder spigots (the part of the cylinder protruding into the crankcase) could also be found down there, having been beaten to bits by the con rod stubs.

Do you think that it would have run on only one cylinder if it had been colder? I wonder if there is a chart some place that shows the relationship between temperature and cylinders?

I think it was a gift to run on two cylinders.

How many pushes did you need to get back home?

i know it's off topic,. i had the same problem.

you can't use deterent oil in an engine that does'nt have an oil filter.

you can't use deterent oil in an engine that does'nt have an oil filter.
This is an old wives tale. The only hazard is converting from non-detergent to detergent after the engine has many miles of non-detergent oil running, where there is the possibility of all the built up crud overloading the oil. Many motorcycles, lawnmower/generator engines, air cooled VW bugs, etc have been running on detergent oil for decades. Since at least 1958, and possibly earlier, VW has recommended HD (high detergent) oils in their aircooled engines.

your right. i should have said "never put deterent oil in a new "used" engine that does'nt use an oil filter". i junked alot of used vw engines that way.

And that brings up another problem when one only tops off low oil levels. The oil level was based on an empty oil pan. Your dear aunt's oil pan was not empty when she had the oil drained. If it was 1 inch thick, then the person refilling the oil pan would only need to add 2 to3 quarts of oil to reach the full mark. Good thing he checked, he almost added too much oil to her car. Heavens knows what that would do.

As long as you don't chemically/thermally/physically damage the base oil itself, that base oil is OK.

It's the additives that break down over time. That's why you need to change it regularly. Changing oil regularly is a lot cheaper than replacing the engine.

not going to repeat the content of the GA's below except to mention that interstate semi trailers that we used were able to change their oil change specifications from every 10,000 km to every 50,000 km , simply due to increase in the quality of engine oils over the last 10 years.

oil sample testing is carried out at every oil change

the above comments do not apply to "home brand" oils , i am talking about high quality oil brands

the outcome of the oil tests showed that improved oils permitted extended service intervals , and thats in deisel engines which are generally considered dirtier than petrol.

on a side note , generator sets which run on methane gas produced from refuse / landfill can run 20,000 _hours_ between oil changes and the oil comes out clear and clean like it was new.

note that 20,000 hours is roughly equivalent to 2 million kilometres of driving

Actually I do not use oil in my street or racing engines. I use an ester normally sold under the pseudonym "Synthetic Oil." A bit pricey, but well worth the cost. Much better at 8,500 rpm on the steel valve parts. On street engines, no broken rods, ever! And I change the "oil" religeously, never going over 8,000 miles. I also use only iridium plugs. Platinums are a rip-off.

Ok, I'll be the smart a**

Why are you putting oil in a motor?

We fill motors with oil all the time. And then we add a spring loaded reservoir to keep the pressure a little higher than the ambient. That way sea water doesn't get into them when you go under.

I never understood why they call it motor oil.

You are free to believe as you please.It will make no real difference to the engine.Only the facts will matter.

When an engine is first started, it is cold, and condensate forms inside of the cylinders as well as liquified gasoline contacting the cold metal of the engine.Once the engine warms up to around 195F, the boiling point of gasoline, the engine begins to drive off the accumulated water and fuel form the oil pan.The PCV valve assists in this by providing a slight vacuum in the crankcase and re-injecting the fumes into the combustion air stream.During the period of warm up, the oil is contaminated by water and fuel.This mixture has a degrading effect on the oil,that is it modifies the anti friction properties, as well as the anti-corrosion properties.

There can only be a certain amount of additives in oil without having a degrading effect,so there is a very precise amount of proper cleaning and neutralizing agents added to the oil.Eventually, these chemicals become "used up",imagine putting baking soda into vinegar.At first, the reaction is very strong, and the mixture is still acidic.Add more baking soda, and it reacts some more.Keep adding baking soda till there is no reaction.At this point, the baking soda is used up,converted into a salt.It cannot neutralize any more vinegar.If more vinegar is added, the mixture now becomes acidic again.This is a simplified scenario of only one reaction that happens in oil over multiple heat/cool cycles.There are many more reactions that occur, but I will not get into that here.

Theoretically, if you had a perfect filtering system, and laboratory testing of your oil, you could determine when to add,and what additives were needed to restore it to original specifications.If you can afford this, then go for it.

Major fleet companies do this when the cost can be justified.Some diesel engines require GALLONS of oil, not quarts,multiplied by hundreds of engines, the extra cost will pay for itself.

Do as you please.It is your money to spend or waste as you please.

You have been advised.

Good luck.

Engine oil has a number of different spec's that the API ( American Petoleum Institute) checks to rate it's quality or qualities.

How well the oil lubricates is important, but a motor oil can go a long time and still lubricate. It won't be as good as it started out as it is loaded with carbon and wear metals the longer it is used.

The main reason that they tell you to change your oil at a certain interval is because it is broken down by the combustion process over time.

When an engine is started in the morning moisture comes out of the iron and is mixed with the oil for a short period of time. The combustion gasses mix with the water that is formed and creats sulfuric acid. Every good oil has a TBN ( Total Base Number) that is the oils ability to neutralize acid. The TBN is depleted over time and it can only neutalize so much acid and then it is depleted. Once the oil can't neutalize the acid, the acid starts to dissolve the metals in the engine. The first metal to be affected is the lead overlay on the bearings. That's why an engine that has not been maintained correctly usually meets its demise with a catastrofic failure. ie siezed bearings or a repair indicator on the side of the block. That would be whole with a rod sticking out.

The oil has detergents that keep the sludge suspended till it can be drained out. If you have oil that turns black very quickly, it's for one or two reasons. It's either a good oil that is keeping the carbon suspended, or the engine has excessive blowby.

Oil change intervals can be adjusted by how the vehical is used. if you do a lot of highway driving, the oil can be used longer than if you only go to the store and back. If you only drive short trips there is not enough time for the water to evaporate, the oil has to work harder to neutalize the acid that formed.

I had a friend that believed that they only came up with oil change intervals to sell oil. His car locked up at 60,000 miles.

Here is a link that tells you everything you ever wanted to know about oil, but were afraid to ask:

http://www.bobistheoilguy.com/

That was well worth a GA for you Ken!

As you may remember, I have been a fan of full synthetic oil since the late 80's. Sadly (joke!) I have never had to strip any of these engines down to see what they looked like as they were still running with no problems when I sold them. Some with around 400,000 KMs, but mostly between 120,000-140,000 and as all except one was Diesel (one petrol engine with about 360,000 only), they were barely run-in......

VW has all of its engines on fully Synthetic for some years now, at least over here and a computer monitors the usage and recommends an oil change when needed. This was at around 35,000 KMs for my driving, often with a trailer....

Changing to synthetic oil can dramatically reduce the amounts of waste oil that needs to be correctly disposed of, a serious environmental problem everywhere.....

My experiences on CR4 when discussing engine oil previously show that many US citizens have listened to old wives tales about synthetic oils and continue to use old fashioned mineral oil and replace it every 3-5K miles......and they are not open to change........and can be very loud about it, even though they have never used it!!!!

There are even posts on the web from so called "mechanics" telling everyone how bad it is!!!!!

It seems that VW, Mercedes and all the other German car manufacturers really don't know what they are doing telling their European customers to use synthetic oils! With our high speed autobahns where we can often run for an hour or more at sustained high speeds above 100MPH......

I have used it in all my vehicles since the late 80's and never had an engine failure, nor high oil or fuel consumption. I have even lost cooling water and the engine has seriously overheated and still, after a fix (it was 80 Octane Agri Petrol sold illegally as Super in Italy), done another 100,000 KMs before being sold, still running perfectly.....

So I do not believe anyone who has not personally had even half the amount of cars as I have had, with half the amount of kilometers, all with synthetic oil, when he tells me I am wrong.......its the old NIH problem again!!!

By the way, the current Oil I use today is only marginally more expensive than a good quality mineral oil and does at least twice the mileage......

Yeah! I don't worry about disposing of my synthetic oil either...I just wait two weeks until my Jeep blows it out...then add another quart. I haven't changed the oil in years!

Of course, I need to replace the catalytic converters a little more often...they tend to plug up with that un-burnable stuff.

Actually (a simple test will demonstrate this) Synthetic oil just evaporates at overly high temperatures and leaves no residue.....but is far more stable in the normal working temperature ranges, especially when very cold as it flows better....

Whereas mineral oil leaves a coke like residue - which may block a catalytic converter....

Take an old frying pan, place a few drops of each oil on it and heat it up and watch the results......its very convincing.....

I found a good explanation here:-

http://en.wikipedia.org/wiki/Synthetic_oil

I am personally of the unfounded/unproved opinion that a well worn engine may not benefit from Synthetic oil.

I have always used it either from the first day in a new car because the manufacturer required it, or at the first oil change and hereafter.....even if the manufacturer did not require it. I paid extra to have it when servicing on some cars....

I have seen engines that were powered by LP where the engine oil never looked dirty.The oil had to be changed, however, because it still had abrasive contaminants and the oil additives were breaking down.

The black in motor oil is mainly from gasoline wash-down and condensation when the engine is cold, and blow by of the fuel mixture past the rings.A little gets thru even in a new engine, plus the rings scrape the cylinders in both directions.

As for the frying pan analogy,motor oil is a totally different structure.

Oddly enough, the very best lubricant, frictional co efficient wise is Sperm Whale Oil.

It used to be in all extreme pressure lubes, like cutting oils,gear lubes,etc.

Modern synthetics cannot achieve the low coefficient.

However, there is a plant that has an oil that is virtually identical to Sperm Whale oil.

It is the Jojoba Bean oil.

It is a desert plant that takes about 5 years to yield, and at present, the result is used in cosmetics because that is where the most profit is.Eventually, there may be sufficient quantity to be available for the automotive industry.

There is constant research on the molecular structure, and attempts are being made to modify vegetable oils from other sources to duplicate the Jojoba molecular structure.

I hope they succeed.

Maybe one day, we may be able to run our cars with Popeye's favorite oil.

To write such an opinion of the frying pan test showing what happens when very extreme temperatures are reached demonstrates simply that:-

a) you have not done it yourself and

b) you haven't seen it done either.........

If anyone else here has seen it, tell him exactly what happens.

Also, I posted a Wiki link that you have obviously either not read or not understood.....

The cost here in the US is nearly double for synthetic vs mineral oil.And the filters will not generally hold up long enough to take advantage of the longer intervals of the synthetics.

I have been using Castrol for years, and have had several Hondas go beyond 300,000 miles.I changed at 3000 miles or 3 months just to be sure and have not regretted it.

I also changed timing belts before they were due.

All the cars ran good when they were sold, and are probably still running.

I gave one to my brother in law, and he has added another 100k miles, and it still runs good.! (1988 Honda Accord 4Cyl.).

Proper maintenance is the key.

your comment:-

the filters will not generally hold up long enough to take advantage of the longer intervals of the synthetics.

Is totally unfounded on any facts. So speaking generally, what you wrote is wrong.....

The filters in several cars that I had, where the manufacturer did not specify Synthetic, held up for the extended period with absolutely no problem whatsoever.

Perhaps if you run over 50,000 miles on the same filter, you might see a problem, but if you have been reading this blog fully, many have told tales where no oil changes were made, none mentioned a failing filter.......I wonder why?????

As you obviously do not use Synthetic oil, who told you this interesting Tale?

You should not believe everything you hear from people with no personal knowledge.

My experiences with Synthetic oil are all first hand, not second or third hand......

Here is a link supporting my statement about oil filters.Not all fail, but some do.

http://www.motorweek.org/features/goss_garage/the_truth_about_long_life_oil

As for the frying pan test, if your motor oil gets up to the smoking point, it is around 400+F.degrees.At this point, your engine has suffered a coolant loss and is about to self destruct.The normal thermostat temperature in a car is around 195F.

I had a deep fat fryer that I kept hot (375F) at a shop to enable heat shrink gear assembly.It had motor oil in it.I would immerse the gear on a wire for a few minutes then assemble it.This oil never changed color in the 2 years I was there,and it went thru many thermal cycles.

As far as the frying pan, yes, I have seasoned cast iron pans before, and it requires several cycles of heating with a fresh layer of oil in between cycles to properly get a carbon coating on it.Vegetable oil.Not motor oil.The molecular chain is much longer in motor oil than in most vegetable oil (jojoba oil excluded), and takes a much longer time to carbonize.

Note in the link that there are some filters designed for long oil change intervals, and perhaps they are more common in your country than here.

The $4 or $5 frams don't make the cut.

AS for me using synthetic oil,yes I have used it before,but I got no better engine life than with conventional Castrol oil. 300,000 miles is good enough for me.

Perhaps if I ran one till it failed, it would show the benefit,but I will probably never know.I don't keep one that long.I'll check with my brother in law when the Honda finally quits if I live long enough.

You wrote, "AS for me using synthetic oil,yes I have used it before,but I got no better engine life than with conventional Castrol oil."

I have to flag that one. Just how many cars have you compared the difference in oil types and just what have you done to quantify the results?

I am guessing your "testing" is purely subjective.

The difference between synthetics over the old carbonaceous punch of long ago has more to due with reducing the oil change intervals.

I have run synthetic exclusively in a Honda from day one, and sold the car at 300,000 miles with no engine problems.

I ran another Honda,2 years newer, and used Castrol exclusively from day one,sold the car at 310,000 miles and had no engine problems.

True, this is only my subjective experience, but I only have to convince myself,and it is good enough for me.

Only 2 cars, and 600,000 miles does not qualify as objective evidence, but the excerpt from the link above performed a study on taxi cabs and got similar results.They tested 75 taxis for 2 years and saw no difference between the synthetic and mineral oils.

If you run a car hard and fast, or live in a climate of extreme temperatures,synthetic may be better, but for the average driver, it is no difference.

Do what works for you.

Of course, opinions do vary.

In such places as DIESEL Turbo bearings, oil temperature can go through the roof because many people forget that after a hot run, that Turbo can glow dull red hot, that is 700-800°C.......it is usually recommended to run the engine at tick over to let the oil cool the Turbo down for a minute or so.....

Mineral oil will burn and leave residue in the bearings that can require a Turbo replacement, in fact, twenty years ago this was the most usual reason for a Turbo failing to work.

Now if the car is using Synthetic, in a worse case heat condition, the oil evaporates and leaves no residue.

Plus that some Turbos nowadays are water cooled as well, so they never get so hot, but I have never had a water cooled Turbo....

Turbos are used on almost all Diesel Engines and some performance petrol engines in Europe, that is the test of a good oil...here are some pictures to impress on how good a test they are:-

Now do you finally and fully understand the "frying pan oil test"?

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By the way, I had a quick look around and I could not find a problem with filters running out of miles here in Europe......perhaps we just have better filters here and the problem is simply unknown.....

While looking I found this website:-

http://www.tundrasolutions.com/forums/engine-and-drivetrain/36162-best-high-mileage-oil/

There a poster a page or two down says "(And never use Fram oil filters....use Purolator or OEM ONLY!)", a comment I fully agree with, use good quality!!! Then its simply not a problem.....Fram appear to be infamous......

Here is an interesting survey of a particular style of oil filter from many different manufacturers, it demonstrates clearly that Fram filters (and they are not alone) have one third less filter paper than better makes, which probably is at least part of the reason that they are not as good.....

NEVER USE FRAM FILTERS!!!!!

http://minimopar.knizefamily.net/oilfilters/reference.html

Old saying in quaint English, "You pays your money and you have made your choice!"

Buy quality oil and quality filters.....OEM filters are best if you have no idea which one to use......

The final paragraph from the link you provided:

The disadvantages of synthetic motor oils include:

• Potential decomposition problems in certain chemical environments (predominantly in industrial use.)
• Potential stress cracking of plastic components made of polyoxymethylene (POM) in the presence of polyalphaolefin (PAO).
• In July 1996, Consumer Reports published the results of a two-year motor oil test involving a fleet of 75 New York taxi cabs and found no noticeable advantage of synthetic oil over regular mineral oil. In their article, they noted that "Big-city cabs don't see many cold start-ups or long periods of high-speed driving in extreme heat. But our test results relate to the most common type of severe service - stop-and-go city driving." According to their study, synthetic oil is "worth considering for extreme driving conditions: high ambient temperatures and high engine load, or very cold temperatures." ^[17]
• Synthetic oils are not recommended in automotive rotary engines.^[18]
• 
  

Did you actually read them before posting (after I posted them to demonstrate that none of them are really applicable to an average private motorist!!!).

Just to help you, here they are in the same order:-

1) (predominantly in industrial use.) Was in the line of comment!!!! that is not private cars....nor is it non private cars....

2) Few (good) engines have plastics of these types in them. Probably none in modern cars.

3) Taxis get used 24 x 7, the engines run warm almost there whole life, they do not really need Synthetic oil. Its engines that start cold often that REALLY need it.....some Alaskans never turn their engines off, do you live in Alaska, if yes, you don't need Synthetic oil....

4) Do you drive a rotary engined car? Few people do as NSU gave up many, many years ago and only Mazda continued. That is a tiny, tiny population of cars.....

Do you now understand those 4 points are for nearly 100% of the driving population of the world, totally unimportant........

I will agree that synthetics are better in extreme conditions,prolonged high speed,heavy loads, and diesels,or cars with turbos.

But for me, an,average driver, it is extra expense that I cannot justify.

My cars have all exceeded 300000 miles and were in excellent shape when sold,and I always changed timing belts myself.In one model, the valve cover had to be removed to change the belt, so it came off every 50,00 miles.

There was no accumulated crud or carbon on the valve cover, or valve train or head,just a slight smokey discoloration.No build up on anything.This was using Castrol GTX .

The last timing belt was installed at 300,000 miles, just before I sold it, and it still looked the same under the valve cover.

Perhaps if I ran it another 500,000 miles or so, there would be some crud,but the paint was beginning to fade and the clear coat was gone, so I sold it.

Point is, non synthetic has served my purposes well.

We do not have an autobahn, so my speeds were not even close to what you run, only about 75 -80 mph.I do not tow with my car.Our winter time lows are only around 0F,and highs in summer around 100F

I use a 5W40 GTX.

We could each find supporting evidence for both of our opinions, and still it comes down to one thing:Do what works for you and makes you feel warm and fuzzy inside.

To each his own.

PS:I still like your dog!

Assuming for the moment that the Synthetic oil where you are costs double the good old Castrol GTX, (that I used also years ago!), then you can run at least double the mileage or more safely.

Running twice as far on oil that is double the cost means you have not paid out any more money.....

Also you save firstly on (good quality of course, not Fram!!!) oil filters and also on time or garage costs xhanging them both......so it is cheaper financially.

Plus, if I and many others are correct and it actually reduces wear as well as reducing the turning resistance of the motor, you are in a win win situation....

One negative effect that I have personally noticed with Synthetic oil and new cars, that nobody else has mentioned, and the only reason I notice it is because my last 4 cars had the same motor, easy for comparison, but the first was run in on mineral oil before changing to Synthetic at 10,000 KMs and did not demonstrate the problem. It was run in at 10,000 KMs.

The problem being that the running in period, the oil use reduction etc., takes far longer when running only on Synthetic. Up to 30,000 KMs in my opinion, but oil usage, never high even on day 1 with the VW 2.0 Liter TDI engines, further steadily reduces a tiny bit over the first 100,000 KMs.

Such engines have regularly reached over 600,000 KMs and are still running fine.....

By 100,000, you are down to about 0.5 Liter for 20,000 KMs in topping up....almost not worth talking about.....

For me, its a "problem" that simply demonstrates that the lubrication properties of Synthetic are probably twice or more better than good mineral oil, so I do not see it as a problem.....

My car, which weighs about 1.9 metric tons empty, still runs at around 38 MPG US, or 46 MPG UK, when running on the Autobahn at around a steady 130 KM/Hour, or about 80 MPH. It is a Turbo Diesel of course....it has a possible top speed of just over 120 MPH.

2 Liters is a normal sized motor here, but in the USA, it might be considered small. Larger motors have generally a longer life than small ones, but consume more fuel as they are simply heavier generally speaking.....

I hope these comments are interesting for you and many others......they are the result of more than 1 million Kilometers in 6 cars (5 Diesel, one petrol) using various Synthetic oils for engine lubrication and exclusively the OEM Filters.

Andy, I like your posts, and I use synthetic oil. But don't forget, filters are for more than just metal particles. If you put synthetic oil in an old engine with lots of crud, or lots of blowby, and you overload the filter, you may never know, because many cartridge filters have built-in bypass valves.

You are to my mind fully correct.

I am of the opinion, that you should not use Synthetic oil in old engines. How old is a difficult question and has probably more to do with the style of driving and the original oil quality......

Maybe a good idea is to drop the oil pan and see just how "cruddy" the engine is first.....

Not to disagree with any of the GAs previously given, but I have always thought the 3,000 mile or 3 month interval recommended by quick oil change franchises and car dealers is totally a marketing ploy. So in that sense the OP's issue with commercial propaganda has merit. Oil sellers do push the conventional wisdom a bit further than needed to sell more oil.

However, I have always gone by the vehicle manufacturer's recommended maintenance schedule regarding fluid changes and have never had oil related engine troubles (other than leaks!).

Now for a more serious comment or two. My Son bought a 2011 Dodge Calibre 2.0L VVT with the CVT. The owners manual stated an unbelievable 16,000 mile oil change interval. That's right some engineer in Detroit actually put something that stupid in an owners manual.

No it is not talking about synthetics its talking about 5w20 API SN.

We actually ran it the recommended 16,000 miles. Then changed the oil and this was its 0 to 16,000 miles change. It was 2.5 quarts low in a 4.5 qt capacity system and what came out looked more like it had been in a diesel engine for a year not a LEV II gas engine for three months. The folks at the dealership are still advocating 5,000 mile intervals regardless of the owners manual/warranty specs. The folks at Chrysler have yet to return my letter questioning the wisdom of this and requesting data to back up this claim.

There is no actual hard and fast rule on oil changing other than the old tried and true 3 months or 3000 mile litany that has been the standard for damn near ever it seems. The reality is this there are too many variables beyond the manufacturers control to say this is the set in stone right thing to do. As several others have noted large fleet owners do oil testing to govern their change intervals and that is really the smartest way to go.

Not really.

Before synthetics, 3,000 miles was a good insurance policy for the life of the oil.

Synthetics have pushed that mark, in some cases, considerably.

However, the number of miles between changes depends on a host of factors, including how hard the vehicle is driven (service duty), for how long (you need to run your vehicle at least long enough to evaporate and expel any moisture in the engine block), temperature, and amount of environmental dirt and contaminates.

For instance, stop and go driving is considerably harder on the car and oil than the same time driven on a highway.

For most drivers gauging the best time for oil changes is beyond their ability, so a 3,000 mile interval was established as a guideline that would provide a good balance between life of the engine and economy of oil for the range of driving cars see.

Large commercial fleets and municipalities change their oil based on regular oil testing not miles. Samples are taken at intervals and sent to a lab where the condition of the oil is analyzed and reported back to the sender. Not only does this save a huge amount of money by pinpointing when the oil should be changed, but it also allows the fleet owners to catch engine failures before they catastrophically fail.

Oil analysis is something that is beyond most family car owners, but you can do the same thing if you want to, but you will not realize the economic savings like large fleet and municipalities do, nor will get their discounts at the lab.

Ciro, are you wanting to not change it at all or not change it as often as the quick-change shops want you to, that is, every 3,000 miles?

I would recommend you change is according to the manufacturer's schedule, which is ususally at least twice as many miles as the quick-change shop's schedule.

When I was young and foolish, I ruined an engine because I did not change the oil until after it failed and had to be rebuilt. Now I am old and foolish, but my car runs.

My best friend in high school was the son of a state representative who commuted to the capitol daily. He would buy a big Chrysler every 2 years and put around 100000 miles on it in that time, then buy a new one. He never changed the oil or, and this is the hard one to understand, never changed the plugs or points. In the pre-electronic ignition era, this was very difficult to do. If that is how you operate, then changing the oil is probably not necessary. Pitty the sucker who got the car as a used vehicle. But, in those days, 100000 miles was time to scrap the car. Maybe no-one bought the car as used.

If most of the miles were on the highway it will be considerably easier on the oil.

However, I will never want to buy any of his vehicles!

lubricant have 2 functions 1-to clean the friction places 2-to apply a layer on the rotating parts to reduce the friction (we cant make the friction zero) as a reaction of friction the small particles will be added in the oil.and that will make a layer on filter and abstain lubricant to reach on proper places so we need to change it ,after a specified

period .engine oil should be changed before additive depletion and oil contamination can begin to affect engine performance and life.

I think you could add "cool" to your list. That was the big three I was taught as a youngster: Clean, Cool, and Lubricate. As warm as the internal combustion/friction process is, the oil still maintains a lower temperature than the parts that it lubricates/protects.

If you want to know why you should change your oil, have oil sample analsys done on your car, at constistant intervals. Have the contaminantes that are found charted, and then, you can decide just how much of your bearings, rocker arms, camshafts, connecting rods, pistons, cylinder walls and crankshaft you want to watch being added to your oil pan.

LOL!!!!

Good one Bob.

To all that may concern themselves with this topic I myself have had at least 13 Ford vans, all but 2 exceeded 400,000miles and more then 2/3 have gone to 600,000. There was even two of them that exceeded 800,000 & 897,000 respectively. These vehicles were purchased as early as 1969 and as late as 1999, which currently has 223,000. All oil changes were religiously done at 3,000-5,000 miles and some times a little longer, none of the vehicle's that I own are babied all are driven to extremes carrying excessive weight,left running in bad weather until the end of the day, then restarted the next morning. I think I cover the total possible types of extreme's that have been covered here including towing trailers that can sometimes exceed 10,000 LB's. The lubricant changes are at 3-5,000 miles transmission fluid and filters are every 40,000-50,000 miles rear end oil is around 60-70,000 miles never have I experienced a lubricant related issue. the only trucks that did not exceed 300.000 miles were crashed and not repairable. So I think from a perspective of a service person who makes his living by taking good care of his vehicles, oil change are necessary. On some of these trucks I also installed an extra oil cooler and additional double filter external filters using extreme duty filters originally ment for big trucks that use 2 qt.s this gives the system a fighting chance to cool the oil and additional filtration. As I said earlier if you take care of your vehicle's they will take care of you. P.S. all oil's were synthetic except in the very early days before semi-synthetics were out and early on I did have a little problem with seal leakage which is no longer a problem. Duke

At last someone who has put his money where his mouth is and using Synthetics even longer than I have.

Up to now, I felt that I was almost the only one here using such oils.....

Many thanks LOCKDUKE for your knowledge and comments.

Well, I have not been using synthetics since 1969. Started in 1987 and have never looked back.

About the same as myself if I remember correctly......

I know that I only found out about them LONG after they were introduced in Germany....Someone demonstrated to me the frying pan test and I have been convinced ever since.....

I truly believe (I cannot prove it either way) that over the years that Synthetic oil has.-

a) kept my engines working really well and reduced wear at the same time, allowing the cars to be easily sold on.

b) Actually saved two engines (I have only ever mentioned one here) that lost cooling water for different reasons as they both saw a considerable mileage after the event still with us.....

engines running gasoline will comtaminate the oil with acid due to additives, as someone already meantion.

diesel engines don't that problem. they use zinc as an additive. many truck drivers only change the oil filter.

One of the most important reasons oil needs to be changed is that, over time, oil breaks down due to use and exposure to heat. It becomes less effective at lubricating, which causes engine parts to rub against one another. Replacing an engine is much more expensive than changing the oil.

Dear jmmyadam

What is produced when the oil breaks?

What is clear to me now is that there is not a technical reason to change the oil, as far as I see you only need to change some times the oil filter and refill the oil when needed, the rest, I believe, is a commercial invention.

Disagree completely.

But as long as you do it to your engines, I don't care.....

What is produced when the oil breaks?

That thick almost wax-like product that forms around all of the valve mechanism under the valve covers, lifter gallery, and oil pan. I have experienced a build up of this oil by product that obscured the rocker arms. and filled up the oil pan to the point that what was a 4 quart capacity pan now only held 1.5 quarts to the fill mark.

Was this some contrived plan to sell more oil to the uninformed?