Mileage Left in Used Engine Oil

I use the odometer.

I change the oil out BEFORE it is "burnt out and needs to be changed." If there is service life I am disposing of, I am OK with that.

Sulphur content, maybe? Check the TBN and TAN. Subject a sample to a shake test and see how foamy it gets. All of these require a sample be drawn... if suspect and I have to drain a sample, I will drain it all. But we covered that already.

What we used to do on the railroad was take a oil sample, then we would pour it into a test tube with a ball bearing of known weight. There was three test tubes. The first one had 40 weight oil, brand new. The second tube had the fresh sample. The third tube had worn out oil of the same weight in it. All had steel ball bearing of the same weight. You turned it upside down, and let the steeel balls go against the tops of the tubes. Then you turned it back upright, and watched the steel balls decend. If your sample decended a short time after the new oil, then it was still good. If it fell as the same rate as the worn out oil, then you knew it needed changing. This always worked for us. I used the same method in my personal shop on my gas and deisel engines. I had a test tube kit for each . Always was reliable for me. My wifes 2004 Ford Focus has 245,000 miles on it using this method. My Sable has 189,000 miles also. Simple, and accurate.

Will we at least get a slice of the pizza you're eating while we do your work for you?

_{/If so, no anchovies on my slice, thanks.}

Just off the top of my head, either monitor the colour of the oil or use colour change materials in either the oil filter or anywhere you can get easy access to oil flow. As the oil degrades it changes composition and colour.

The normal way people check oil at the moment is based on time between oil changes (somewhat accurate) and using the dipstick to check oil colour (and smell).

Here's another - a simple oil sample test kit - a colour change material you rub your oil sample on (off your engine dipstick) that changes colour as the oil composition changes.

Too complicated? How about a simple colour chart (like a set of paint swatches) that the vehicle owner can compare to the oil on the dipstick to tell visually approximately how much millage is left.

You do what the big boys do - send it out for an oil analysis!

Maybe you should search for one or two, give them a call, and ask them how they do it and what they check for. Then figure how you can do it and what kind of accuracy you might theoretically get.

Works for race cars and municipalities that want to get the most out of their dollar.

Hold on! You've ask two questions here, and it turns out that they are both homework.

We don't do homework here! Homework is where you learn things like, how to perform searches and research independently, instead of having someone else do the work for you.

I, for one, will no longer help you. Bye Bye.

• Do your own homework. CR4 is not a homework cheat site. While some here might relish the opportunity to sharpen up old rusty skills by working the homework problem, consider the following and consider it well. If you cheat on your homework by using someone else's answers, you are only cheating yourself, because the purpose of any homework or other academic assignments is to help you learn - by practice, repetition, and self-discovery.

Lyn is right, you need to do the research your self, the best well learned lessons are learned by your own mistakes.

You'r poor kids.

My kids do their own homework and I help them(THIS DOES NOT MEAN GIVE THEM THE ANSWER) when they need it.

How do you do it?

If you are too cheap or too poor to afford to do an oil change at the proper time then you are likely to cheap or too poor to be out driving around.

As far as knowing when to change, heavy trucks, industrial machines and farm equipment go by running hours not miles.

Oil really doesn't "wear out". Temperatures from an engine are incapable of "degrading" oil. It does, however, become contaminated from carbon and metal, and that's why it discolors and needs replacing.

http://cr4.globalspec.com/member/20555/baxterm-kos-net While I agree with your assesment that oil can wear out, but only for the intended application. The oil would become contaminated, and thin, for its application in a motor. But Niclo Tesla is right also, as oil degrades, but never wears out. It may no longer fit a particular application, but it will work some where else as a lubricant. This is why OLD OIL is collected, cleaned, refined, and put back into service. There are many places that collect used oil, and after processing, they sell it again. Years ago, my Dad would pull his car up to the pump, and Andy would check his oil, and clean his windows. Then he would reach over and get a jug of 30 wt. oil and put it into my Dads motor. It was reconstituted oil. It was also much cheaper. I think it was 10 cents a quart, as new oil was 30 cents a quart. Some of you fine people are probably to young to remember those days. I think Wal-Mart sells used oil. Anyway have fun, thats the main thing. KC0VEA.

I have also heard that the Polymer "chains" get chopped up and the oil gets "thinner". Maybe a method of "borrowing" a fixed amount from the engine and letting it run through a hole into a second container may give some help with that. returning it if its OK and undamaged...

A temperature correction chart may also be required.....

Combine that with some way of measuring how contaminated the oil is....

I did read about a superfine filter system that kept engine oil looking like new as all carbon and metal was filtered out, but under test the oil had lost large amounts of its important lubricating properties before it had covered twice the normal oil change distance (from memory)...

Here is at least one of them:-

http://www.cleanest-oil.com/en/oilwear.php

Just a thought or two.

Thanks Andy. This is most useful info. Cheers

You can start with color, move to PH value and then look at carbon or material contamination. For a diesel engine it is PH and particles are an issue. yOU COULD DEVELOPE a simple reactive test kit that combines color and PH value.

What is in contaminated gas engine oil? Run a spectrum or get it from the oil mfg..

PS, this is worth slices of good Pizza!!

Good luck!

THANKS FOR YOUR ASSISTANCE

I do it the easy way, after the odometer reaches 3500 miles, I pull out the dip stick, check the color and then taste it. If the color looks good and the taste is good I put the dip stick back in and go eat pizza for another week or 500 miles and check again.

If I changed my oil every 3000 miles, I'd be doing it 6 times a year. As long as it doesn't taste burned, it stays for another week. Although there is a time when it looks all brown and really crappy, I do not taste it then, I just change it and the filter too. Then go out for pizza!

Dear--- I have read the replies to your problem. Your situation/ problem has been grossly misunderstood and very wrongly interpreted. Some body is saying RU too poor to change oil in time other says do ur home work. Many more comments etc etc.

As far as I could take your question, you are an Engg. Student and ur Prof. has asked you about practical ways by which any driver could check the engine oil of his car & tell if the engine oil need to be changed or it can go on for some more time.

As and when we take our cars to Motor Mechanic for service or repair, invariably he will check the engine oil. He will ask how many kilometre the car has run after last engine oil change and he will take out the engine oil cap and attached metal strip and take a pinch of oil in his hand and by the colour and viscosity he will tell if the oil is Ok or need to be changed. That all about his experience which is working well so far.

As far as practical ways are concerned there can be few tests like: Viscosity and specific gravity at a constant temperature that can tell you the changes in the fresh and used oil. But as you/ ur Prof. want testing to be done on spot, it is bit difficult because every type of testing will require certain equipments/ instruments, which may or may not be available on spot. The simplest thing that comes to my mind is compare the weight of equal volumes of fresh and used oil, but even for that you need very precise weighing machine/balance.

Another method that I can suggest you is: to drain out oil and heat it to the operating temperature ( aprox. 80 or 90 degree cels) and allow it to cool and settle for long and observe if anything like small metal/ carbon particle, debries etc are settled /deposited on the bottom of the vessel. But even for this you need some arrangement/items.

Without equipments/instruments, the driver need to develop skills of a car mechanic to know if oil need to be changed.

LUV-Dr N P Singh

What a crock, Dr.Singh! Never heat oil outside of its intended usage. It is a dangerous and not simple feat!

Boy, follow instructions of the owner's manual or develop a pattern for changes based upon your duty cycle. The "Clean" oil is really superfolus issue. Oil will stay within its intended requirements for much longer than it is "Clean". This study is a maintenance program issue, not about when time your change.

If you ever drove or worked on diesel engines you would know the oil is typically pitch black within a few miles of an oil change. You can't determine soot loading by smearing it on your arm. Because doing it that way you would be changing it several times a day....when it was still good for thousands of miles even in severe usage.

And the OP never gualified WHAT the oil was used in.

The only way to know how close it is to "worn out" is via a profession oil analysis. Anything else is taking a wild guess.

And if it 'irritates', it's possibly a tad acidic

Oil spy

Mainly what ends up being added to the oil are: water, acid, carbon, metal. When are these excessive? How do each of these affect the surfaces being lubricated?

When is oil no longer adequate to lubricate ie to keep two surfaces apart hydrodynamically, maintain viscosity, and conduct heat away from the surfaces?

Tests for these?

Use a color ocde chart to determine the life of the oil. You can break it down by weight (5-W30, 10-W30 ect) and then run some tests to deterrmine how fast the oil is breaking down. It goes in clear gold come out black as night.

Place my vote on a simple resettable hour-meter or countdown timer. Once a baseline has been established pick an appropriate amount of hours of engine running time.

For the average car owner/operator, monitor the levels often to make sure there is not a sudden change indicating oil burning or fuel leakage. Smell... Learn what new oil smells like then you'll know that rancide/burnt smell. Looks... Take small smear on your fingernail and move it around in the light of the sun or other strong light to see if there is any sparkling indicating minute pieces of metal. Also if THE color is muddy looking. These are rough indicators that any one can do at any time without no extra gadgets. Shine up the dip-stick with fine sandpaper to make reading easier.

Saab's currently come equipped with an oil service life meter. It doesn't measure any actual oil properties, but it assumes the remaining service life based on time and engine load. Before the company had turned into GM's unwanted stepchild, they were working on possibly installing viscometers into the sump to measure oil quality.

Diesel engines are great at ruining oil. They have a tendency to shear the molecular structure and permit unburned fuel to migrate from the combustion chamber into the oil sump. Both will reduce the oils viscosity and ability to protect.

Check out Blackstone Labs. They have an oil analysis service which measures oil quality and contaminants such as fuel and metals. The metals test is useful in estimating engine wear.

Petrol engines do the same, especially when only used for short runs. Then you drive on a long run and all the petrol and water cooks off and leaves you with a quart of oil missing.

At least diesel oil lubricates to a much higher degree than petrol ever does!!!

Hence the saying "It only uses oil on long runs!!"

Diesel was used as lubricating oil for a short time by some people years ago to clean out a dirty motor (diesel or petrol I believe,, but only at tick over, not driving........never done that myself....

I want to comment about the complaints about doing someone's "homework" for them. If I ask a question that relates to my field of work, are you going to complain that you are doing my "job" for me, and refuse to help? If so, I think you should go somewhere else where you can be just as useless. Whatever the reason someone is here asking for help, beyond building a bomb of course, I think they should get a polite answer to their question.

I saw a Texas prison warden interviewed one time. He made a classic statement. He said, "you can't rehabilitate someone who hasn't been habilitated in the first place". That still makes me laugh. I think the same applies to attitude. You can't expect people with a negative attitude to post positive comments. It's a forum, as long as people follow the rules of the forum everyone is welcome. Manors aren't mandated.

Don't rag on me, answer the question!

I hope he is talking about an old out of warranty vehicle. If it is in warranty and you cannot prove keeping up with the mfg maintenance schedule, well is guess it is out of warranty after all.

Try checking with one of the oil analysis companies. The service department of any big truck dealer or leasing co should be able to get you a name.

My concern with a simple test is that so much goes on with the ageing of the oil, the test you perform may show everything is OK and something you are not testing will bite you.

just an un-educated mans opinion. -- JHF

Hi There, Just had a call that we were given as an solution in your quest to research ways to check the service life of oil. Happy to help a student, and if you send me some details I will send you an OIL-SPY kit as a freebie from UK. Rgds Larry

Dear Larry,

Thank you for your kind offer. I cannot resist it, so I shall accept it.

Please forward to:

Chris Constantinides, 12 Dimitros Str., GR-15342 Agia Paraskevi, Athens, Greece

Will send you my comments soon after I use the kit.

Kind regards, Chris

No problem.

If you wanted to measure oil viscosity, and easy approach might be to fill a known volume and measure the time it takes to empty (or change from one level to a lower level). You would need to test this out to see if the difference in drain time between new and used oil was measureable and repeatable.

In my opinion this might not be practical as the temperature of the oil at the time of the measurement will affect the viscosity reading.

This is why I like CR4...

A seemingly simple question is asked... actually a pretty good one..

It's one that we should all have a similar grasp on the answer.. but do we?

The voodoo is sorted through and all the while we can enjoy reading the various answers while we each gain a bit more insight.. (at the very least) in a rather pertinent topic.

we all win!.. ...and much like a radio call in show.. there's a guy chiming in to gripe about the subject "because he listens all the time" rather than changing the channel!?

lyn.. i support you reasoning.. I do..

tho.. it seemed like you had your "auto response" activated considering how up front the op was.

keep up the good posting..

to the op..

...I just look at the oil.. if it look's disappointed, I know our relationship is over.

This may be a shot in the dark, but you might be able to do something with electrophoresis.

Does this mean I don't have to taste it any more?! Tongue is being degraded monthly.

Hey, your original technique was pretty easy...when the yuck factor reaches about 7 on a scale of 1-10, it's time to change the oil.

Reminds me of the Cheech & Chong routine about feeling, smelling, tasting, etc., some dog poop, and then deciding better not step in it.

Amazing, 61 comments and nobody mentioned the "thing" that "wears out" in modern motor oil, the additives. A lot of the properties of motor oil rely on the additive package that characterizes and "tunes" the oil for its particular duty/rating. Many of them are sacrificial and once gone, the oil no longer can perform all its intended functions.

Sure lubrication is at the top of the list, but there's also: buffering for ph, suspending solids, maintaining/adjusting viscosity, resisting temperature breakdown, etc., etc. Just looking at the oil tells you more about the condition of the engine than the condition of the oil (dirty, sludgy, overheating, etc.); i.e., put clean oil in a dirty engine, voila, instant "dirty oil".

The only way that you can tell about the chemical properties is through chemical analysis. Once the tester knows the make and rating of a particular oil he knows what the baseline quantities of the additives is, and then compares the sample against the baseline to compute the percentage of the additive package remaining in the oil sample. All those rules of thumb are nice and worked just fine when oil was a much simpler product, but that's no longer the case.