5w vs. 10w oil

"I put 10w30 oil in, but supposed to use 5w30 oil. I did not notice until I put it in."

"Will this grade hurt my motor/engine?" NO

5w 30 motor oil is useful where you might encounter lower temperatures. You will not notice any difference between the two.

To expand a bit, the discussion is about 10w30 vs 5w30 motor oils. Both are basically 30 weight oils with the addition of pour point depressants to achieve a wider operating range.

There will be NO noticeable difference in the use of one over the other except in a colder climate and then the engine will start easier with the 5w30.

#5 and #10 weight oils are specifically produced to have their respective viscosities.

The lighter weight oils are used to meet EPA standards for efficienct and pollution. Lighter oil has less resistance, hence better fuel mileage. They also burn more cleanly when they leak into the combustion chamber, hence lower pollution. The down side to this change is that there is less lubricity in the thinner oils and therefore more wear. I always opt for the 10W-30 option as a result.

You will get better gas mileage with the 5w than the 10w.

No, it won't damage the engine, but the 10W 30 grade could make the starting system cough a little more when starting a cold engine. When the oil is up to operating temperature the viscosity is then effectively at the 30 level and there should be no discernable difference in operating conditions, but you would see differences in fuel consumption if your journeys are more of the cold start/stop/cold start/stop type than continuous hot running type. The 10W 30 cold oil will protect your crankshaft bearings better than the 5W 30 cold oil. In the intermediate temperature range when warming up through the first few 10/20 miles or so the bearing oil film thicknesses, that is the dynamic oil film generated by the rotation of the crankshaft in the bearings, will be thicker with the 10W oil than the 5W oil and provide better separation of the crank from the bearings. This is especially so at high engine speed/very low throttle conditions and low speed/very high throttle conditions. So use the thicker oil with confidence with the possibility of marginally longer engine life but marginally lower fuel consumption.

I agree with most of what you wrote except this:-

The 10W 30 cold oil will protect your crankshaft bearings better than the 5W 30 cold oil.

A 5w oil protects an engine designed for this oil better in my view.

Why you may ask?

Simple, the "thinner" oil gets to the working parts quicker ESPECIALLY in cold weather and ESPECIALLY if the engine has not run for a day or more..... Which is why such oil is specified in the first place by the engine manufacturer.......!!!!

It also protects earlier for the dumb Bunny that has his foot on the gas the moment the engine starts!!!!!!

Always let the engine start without touching the gas pedal. Then let it idle for a few seconds at least.

If it won`t start without giving gas and the engine is relatively new (built in the last 10 years or so eg. with a motor management system) then something is wrong!! Get it fixed......

Thicker oil is really only needed if you live in a relatively hot climate, many car manufacturers put a graphic in the car manual giving the average temperatures and the oil type to use, or at least they used to, I haven't looked recently I must admit.

I have only used full Synthetic on many different cars since 1989....I have not replaced an engine, several ran to nearly 400,000 kms.....and were sold on in a normal running condition....

Andy, what's your take on oil viscosity modifiers such as Lucas Oil Stabilizer? Do those honey like concoctions "improve" the viscosity and "stabilize" the lubrication properties of any motor oil as claimed?

There are many of these oil additive products. My grandfather used a honey like oil product product from Germany named "Ejax" in his tractor. I was told later that Ejax was the original name for STP. Recently I watched fascinated at a local fair as a local representative for an oil additive company repeatedly revved a Chevy 350 without an oil pan or any other means of lubrication.

Of course I can be fooled by trickery but the engine was not dripping any oil. As I passed nearby several times during the day I could hear it's high RPM exhaust note ripping through the noise of the roller coaster nearby.

Years ago I had a car that the oil pump was worn and I used STP to keep the oil light from flicking on when hot......

......But I do not use anything like this now for many years as I have been a convinced Synthetic user since 1989. I have had several cars that I sold over the years since that ran like new and had over 350,000 KMs, one petrol and several Diesels. The rest of my cars I usually sold around 120,000 KMs and the oil usage was almost zero, 1/2 liter in 15,000 kms or so. One Sharan, would need 1/2 liter as the next service came up....

I never rev the engine when starting and I drive maybe 1/2 mile before using any large amounts of gas pedal......Also, as most of the engines I have had over the last 20 odd years have had Turbos, I make a ritual of 1 minute tick over before switching off after running down the autobahn....I have never replaced a Turbo either!!!

If your car is relatively new, less than say 100,000 kms and uses little oil, I would advise anyone to go for Synth and longer change intervals, its good for your car, good for your pocket and better for the environment. Getting US citizens to do this is like pulling teeth!!

(disclaimer: all this info came from a local mechanic that owns a vehicle with over 300,000 miles on it and still running the original engine...so I'm taking his word for what he said)

The first number has to do with viscosity when cold and the second number when the oil is hot.

Thus 5w30 and 10w30 are different under colder conditions (5w being less viscous) and the same under hotter conditions. 5w30 makes a big difference in the cold but also pumps a little quicker into the head of the engine on startup in case you like to start-n-go without allowing the engine 30sec-1min to warm up.

On that note, worn engines have more wear and larger 'gaps' so thicker running (hot) oil is a good thing. i.e. 10w40

High performance engines and others machined to tighter tolerances than usual use thinner oil, 5w20.

Hope this helps.

Only if you start and drive your car in -20 degree conditions for lots of short trips.

I've been told by an automotive mechanic to just use 50w and my car will leak less.

I do not know what to say about an engine that leaks oil and is not being repaired or replaced, without being rude. Sorry......

The environment does not like oil in it.

Well some of us haven't always been in the position to buy a new car every 3 to 4 years. In fact some of us are lucky that we have a car to get from point A to point B.

As cars get older they tend to start leaking oil whether you like it or not.

Your comment neither supports nor discredits my statement.

The statement made by this older man, who has been deceased for about 7 years now, has not been confirmed by anyone else.

I want to know from someone with a little more theoretical knowledge on the subject to give me an answer.

That guy always used 50w. We're in an agricultural area. He also produced olives and oranges along with operating a garage for automotive repairs.

My take is if an engine leaks, it should be repaired.....does you engine leak?

There are plenty of old cars (in many countries) with well maintained engines that do not distribute oil around the place....

No my engine isn't leaking.

My question is:

What would be the value of using 50w oil in an engine? All the owners manuals that I've read recommend using 30w.

The conversation came up several years back while rebuilding an engine on my car, when it came time to putting fluids in the car, he made the statement.

I'm not an automotive mechanic but I can find my way around an engine to maintain it.

I have a friend that rebuilt an engine of an old '69 Morris Minor and after reassembly he had to "run in" the engine for a certain number of miles with a heavier weight oil. The bigger number (to my knowledge) signifies the viscosity when hot. The heavier oil helps protect the engine during this run-in period...not good for fuel economy (the engine should be ran rich too so temperatures are lower) but it's a temporary stage while the parts all get settled in.

Thank you.

I think that with an engine in a normal condition or better you would be putting more fuel through the engine, unless you live where it is very warm most of the time...

Also, I tend to think that it is not synthetic (I could be wrong!) and I find synthetic allows longer distances between changes, a longer life for the engine and better for the environment too....

...but Synths are not for just any engine.....!

Depends on which engine you have. My shop is a member of AERA http://aera.org and one of the tech bulletins we received was:

Revised Lifter On 1989-98 GM 1.0L VIN 2 & 6 Engines

AERA members report a revised lifter for 1989-98 GM 1.0L VIN 2 & 6 engines. These engines are used in GM Metro and Firefly vehicles. Previously In 1992, AERA published Technical Bulletin TB-1054 concerning a revised lifter. The part number listed in that bulletinis now outdated. The information contained in this TB supercedes all previous lifter information published for this engine.

According to GM there have been several revisions to the lifter since 1992 and the current lifter part number is 25178085. GM has suggested to always ask for the most current part number when ordering a lifter for this engine. These revisions have been made in efforts to control the lifters bleed off rate.

The correct operation of this revised lifter is dependent upon the use of only a SAE 5W-30 weight oil. Apparently, when thicker weight oil is used, an inability may exist within the lifter to bleed off oil quickly enough to prevent full extension of the lifter. This is most noticeable at higher engine rpm while oil pressure is the greatest. If the engine is allowed to operate in the above-described condition, a burned valve may result.

The AERA Technical Committee

We HAVE seen our share of these heads with burnt exhaust valves, and in most cases when asked, the owner told us he had been using 10W-30 instead of the 5W-30 oil the manufacturer called for with that engine. Best to go with what the manufacturer recommends, they spend the BIG $$$$ figuring out what works best. (MOST of the time, they screw up big time sometimes too)

Ken

THANK YOU! This thread has had its bits of education for me.

Most of my oil knowledge can be considered a bit dated, subject to cold weather operations, and subject to using well worn engines of 1960's-1970's vintage.

For cold weather, I've always used multi-viscosity oil. Area I grew up in had temp extremes from -40F to 95F. The worn engines I had I would use 10W-40 or 15W-50 oil depending on season.

I've always changed oil at 3000 miles (5000km) to get the dirt out of the engine, not necessarily because the oil was used up.

The moral for me is to refer to the owners manual for more current data.

We are looking to replace a high mileage van (150K miles) and I will probably start using a synthetic oil, since that seems to be the trend and the good reports I've seen on this forum.

Also, engine assembly today is quit a bit more precise so engines do run somewhat smoother and can benefit from lighter oils.

WOW who would have thought?....but it fits perfectly!!

Many thanks.

Well, I just learned something. If the poster checks it is "off topic" then all that shows is the number.

You can click on the number and read the post but it doesn't show. New feature?

Or I'm a slow learner!

How many knew to click on the number to read the post?

Ken

I knew that! And you're not the only one who's slow! If you know what I mean.

And I also get distracted and drift off the main topic often.

You can set it up to show or not show....

Ah, my stupidity is showing up fine this month it looks like. Thank you Andy. I went and set it so they show like the rest do. Geeez, it is the off topic ones that make me laugh usually, why would I want to hide them? :)

Ken

I would not class that as stupidity as I believe that we all got caught out with that when they first added it.....

....or we are all stupid!

That's right. In one way or another, we are ALL are... else why would we be looking for "therapy" on such a places like CR4? LOL

Because we sure aren't on here because we were "told" to be on here or else.

For a lot of "us" it has became our extended family I suppose. Nothing wrong with that as long as we keep our cultures from interfering with it ("our extended family") or causing too many problems.

And many of these forums DO lead to us hopefully learning something new everyday...

UNTIL "they" (the guys on here running it) spring something new on us.