Forgive this oil thread, could old oil be OK???
 

I have the 98 C230 with the spooky 4 cyl engine that doesn't burn ANY oil. I am coming up to 10,000 miles since the last change with Mobil1 0W40 and I checked the level and it is still right at the max line. And the color is a brown amber color. On the one hand, some will condemn me for letting it go so long, and I have previously been an "always change at 3K" guy with other cars. But I feel like I will be draining out perfectly good oil. If it uses NONE and still looks good, and was Synthetic to begin with, is it possible I can go farther on it with a clear conscience? I am looking for scientific answers here, not religious. I admit it is a question I never thought I would have reason to ask, but I never imagined there was an engine like this.

Thanks,

Mike

You'll get 2 kinds of scientific answers. One will say leave as is; the other will say change it now, so in reality, science and religion in this regard, are one in the same.

You have what I suspect is a nice car. Why would you want to gamble with stretching it's most important lubricant any farther than you have?

Change the oil and forget science and religion.

One inescapable fact is that so far, oil is cheaper than a new engine.

Oil slowly breaks down over time. This is an inescapable fact. Normally, you can tell bad oil easily by its black appearance. Just because oil is not carbon-polluted doesn't mean it's still good. It can break down, or have its additives corrupted by metallic components from your engine. The best way to find the ACTUAL condition of your oil is to have it analyzed. Only then will you TRULY know if it can go farther or not. From the sound of it, you're unsure - if you drive it every day, change it, and analyze what you took out - you'll know if you can take the next change further safely AND you'll have safety of mind while you wait for the results.

Not only can analysis tell you alot but so can an engine rebuild:eek:.

Send it to the lab, everything else is guessing.

A 10,000mi engine oil has generally reached its life limit.
Color does not tell much.
Engine oil gradually loose its original properties and more importantly, the additive package slowly disintegrates while it is being mixed with all kinds of contaminants. (acid, ash, carbon, rust, silica, gasoline residues and about 10 others)
Oil analysis: Don't necessary rely on those.
You'll never know if the results you'll get are accurate.

proof? Have 5 samples taken of the same oil coming from the same car at the same time and sent them to 5 different oil analysis outfit.
You'll be amazed by the results. They will all be vastly different.

^ what he said. But change it and and Send a sample of the old oil to http://www.blackstone-labs.com/ they'll let you know how well it did and so you know for the next time.

Looks like my curiosity will cost me 20 bucks. Sample kit ordered. Thanks for the info. I do not have the funds to test at 5 different places however. But hopefully this one will give me an idea. I will probably keep changing the oil at 10K with the Mobil1 0W40 but it will be interesting to see the results.

Thanks,

Mike

Its worth $20, and worth doing once in awhile if you are into it. If you want to extend oil changes its a must.

Any lab will do, I have used Blackstone with fine results. If it was a $100k+ engine then yeah sending samples to a few labs is probably a good idea.

I always work with the concept of "if in doubt change it out".

As for engine oil analysis. Yet another thing from the aircraft industry that has come to cars that really does not do anything for you. Unless your really familiar with the engines and the way they are "supposed" to wear and familiar with a fair amount of metalurgy the pretty printout you get is pretty useless. What exactly can you do to stop your engine from wearing out? More frequent oil changes might make you feel better but its not going to slow the process much when you have a problem of some sort. The only thing thats going to change things is "going in" which in all reality will probably cost very close to an engine overhaul or used engine. In some cases your better off by just waiting for the engine to fail and then go in to see what happened in there.

In private aircraft oil analysis is used to determine engine overhaul times. Many owners will start doing oil analysis when they get near their TBO time to determine how far they want to go before biting the bullet on an overhaul. Many owners will go over their TBO time based on the oil analysis. In a plane oil analysis is useful because the engines are so critical. No one is going to die because their engine blew on the expressway but if your flying over cities or water and your engine goes your in bit of a pickle and you better hope there is a nice open field within gliding distance. WIth aircraft engines there is a weath of data that will can actually tell you what your analysis number mean. With a car there is no such data. So if your suddenly seeing a lot of aluminum in your oil your only answer to the problem is really just an educated guess that may just be part of the engine's normal wear process.

Got the test results back today. Everything was within "universal averages". I paid an extra 10.00 for a "TBN" test which they have very little explanation of other then it tests for existance of the additives. They say that diesel oil starts out as "11" and gas oil starts out as "8" and 1 is considered low. Mine tested at 2.3 so they said I could have gone another thousand or 2 thousand miles. Well I think I will stay at 10,000 mile intervals and probably won't test again but it was interesting.

Mike

When to change oil?
 

Oil is SO low cost compared to ANY engine part. Be aware that new EPA rules requiring 'oxygenates' and Congressional inaction have forced gasoline blenders to use ethanol a lot. This radically changes the crankcase chemistry. The very low TBN value of the used oil test (around 1.0) is testament you werr on the ragged edge of engine corrosion, and probable getting some in the piston ring belt area.

If you want the engine 'as new' for many miles, cut the oil change interval to 5K miles and use a premium 'dino' oil if you don't want to spend the money. However, IMHO, this is false 'economy.' How much does gasoline for 5K miles cost? $700?

Mike, I take it your car doesn't have the FSS indicator? I run this same factory-speced oil in our car and change it out around 10k miles. I've performed UOA on the past two changes. The results have been virtually faultless. Based upon what I've found via UOA, I'm going to start changing the oil no later than 10k miles regardless of the prediction made by FSS.

You might wish to change earlier with a 4 cylinder engine. As hatterasguy mentions, it's nothing but guesswork changing the oil with short intervals.

Take care.

The manual says it has FSS however it just counts to 10,000 miles, so it is really not very "flexible".

Mike