When to change your oil

I change my oil when it starts to look dirty. I see no sense in a 3000mi oil change when the oil is nice and clean…

You can’t tell the true condition of the oil just by looking at it. The additive packages break down over time. For my Mustang since it does run forced induction, I do 3k mile intervals with a synthetic oil. For my F-150, It’s 5k oil changes with a semi-synthetic, usually Motorcraft since it goes on sale frequently and meets all OEM specs. For the TR6, since it’s only driven in the spring and summer, and then usually for only a couple hundred miles a year, I just change it annually every spring with Castrol 20W-50. Alot of it leaks out anyway.

Thanks for letting us know, Peacefrog.
I had been wondering how often you change your oil.


I find it hard to believe that oil does Not change color when it degrades

I take it … this is a fairly new vehicle…

So according to you…since my oil is dirty at around 1k miles I should change the oil every 1k miles.

It’s IMPOSSIBLE to tell how well the oil will perform by looking at it. To truly know if the oil is still good you need an oil analysis. I personally think this is nuts…but that’s really the only way to tell.Do what the owners manual says…probably close to the 5k miles mark …it should be fine…Exceptions to this are turbo’s or cars that are known to sludge…then you want to change every 3k miles and probably use synthetic.

So where did you get your degree in chemical engineering???

This crowd can get rough at times…

I’ve attached some links to sites that have good information on oil


I recoomend a visit to each.

Contamination of the oil by wear particulates and by combustion blowby do discolor oil, but oil is subject to other degradation that may not, such as shear damage to the molecule chains and depletion of detergents that wash your cylinders and parts just as the detergents in your cloths washer help wash the dirt from your cloths. In short, while your approach would sound logical, it’s based on an erroneous assumption.

Oil is cheap. Engines are expensive. Oil in the lifeblood of your engine. It lubricates, maintains a pressurized barrier between your crankshaft bearings and the machined crankshaft surfaces, removes heat from the cylinders, and washes the insides of your engine. It has multitudinal responsibilities. Keep it fresh, at least as fresh as the manufacturer recommends, and your engine is unlikely to wear out prematurely. Try to stretch your time between oil changes and your engine’s lifeblood will not be fresh…and you increase the chances of the engine wearing out prematurely.

Personally, I like to go no more than 5,000 miles between changes.


Even though the manufacturer of my car specifies 7,500 mile oil change intervals, I see fit to ignore that advice since I usually keep my cars for 8-10 years.

Without trying to sound paranoid, I really think that car manufacturers nowadays are recommending very long oil change intervals in the hope that most of their customers will sell/trade their cars in 3-5 years.

If someone gets rid of his car within a 5 year period, it is likely that the second (or third, or fourth, or…) owner will be the one who pays the price (literally) for failure to change oil often enough. If I got rid of my cars after that short a period of time, I might also “buy into” the concept of extended oil change intervals.

However, since I am more interested in extending the life of my engine, as opposed to extending the life of my motor oil, I refuse to go more than 4,500 miles between oil changes.

Am I paying for more oil changes than might be absolutely necessary?
However, I prefer to err on the side of caution, and as Mountainbike says, “oil is cheap, and engines are expensive”.

3000 miles is typically recommended for severe service. Most people don’t do the short hops, drive in extreme dust, or drive in extreme heat that might qualify as severe service. If you have an oil life monitor that actually monitors engine conditions, you can go by that. They have been around for more than 30 years and have been peer reviewed at the SAE. If you don’t have a modern OLM, change between 5000 and 7500 miles.

I cant believe you all are falling for this post. And the REGULARS TOO…


maybe some people are just bored and exercising their fingers.

I’m having nightmares of a 100 post indy thread. AAAAAAAAAAAAAAAKKKKKKKKK!!!


Lacking reason to believe otherwise, I always assume that the question is an honest quest for information. I’d rather help someone who’s “pulling my leg” thqn refuse to help someone who’d really in need of help.

It’s possible that I’ve been fooled, but it’s equally as possible that I’ve helped someone understand the importance of oil changes.

Perhaps I’m just too naieve.

Its ok MB, you’re forgiven…


Unless the car is brand new, change the oil every 3,000 miles and follow the rest of the car manual’s fluid change recommendations. The rest of the car might well fall apart around the engine, but at least that will last.

20 years of driving and the 3K change has never failed me.

Good point. I tend to agree. Better to change it more often if you don’t test it to find out when it should be changed for your driving pattern.

I also sort of agree the manufacturers assume the car will be traded. Well, not exactly. It’s just that they do not tell me how the decision was made. When I don’t know how a decision was made, the decision means nothing to me.

I am on the other side of the fence on Peacefrog’s statements. I tend to think his oil is not bad and does not need changed when it is clean yet. This is a perfect case for him to have it tested when it starts to look dirty.

I have been driving around 50 years, and have never seen clean oil after any length of time, except my Mobil-1 EP, at well over 5,000 miles.

So, Frog, what is your driving pattern, and car and which oil do you use?

26 years of driving, and 5K oil changes have never failed me.

He’s earned it. I’m still laughing.

true 5K is a good standard, but Toyota had a few issues with it.

Let me add here that the Blackstone test of your oil tells you much more than when to change the oil. It tells you a lot about the condition of your motor. The condition of internals such as valve train, blow-by if any, head gasket leaks. It’s like having a miniature mechanic crawl though your motor checking the parts.

I did it only because of the conflicting information here,mostly guesses, on when to change oil, and found it was a very valuable thing.