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Question about oil change intervals, time limit

I don’t really see the reason behind the monthly limit on oil change. Let’s take a hypothetical case:

New car, you drain the oil, change the filter, add new oil. Now leave the car untouched for 12 months. Why would you have to change the oil? surely the oil doesn’t age, it’s been in the ground for millions of years. There is no expiration date on it (or is there?)


If the car sits unused for a year, the oil doesn’t deteriorate. My guess is that there is a time limit because if a car is used very little it may be because the car is used for strictly short hop around town driving. This amounts to severe service and that is the reason for the time limit.

Oil in sealed bottles doesn’t age. You can grab a bottle of oil that’s 10 years old and if the specifications of the oil meet the requirements of your car you can use it without problems.

Now take 6 quarts of oil, pour it out into a dirty pan that’s as full of sludge, fuel vapor, moisture, and combustion byproducts as the inside of your engine and leave it out in the open air for a year. How confident would you be in using it in your engine?

You can’t seriously be comparing refined motor oil to crude oil in the ground.

@triedaq I agree! We have 2 cars that are driven relatively little, but get to go on long trips (over 100 miles) regularly. The dealership keeps pestering us to bring the cars in for oil changes with only a few miles on them since they don’t know our driving pattern.

My neighbor down the steet is an 80 year old widower, and his 2004 Focus has had 5 oil changes. He should change a bit more often since he does not take long trips.

As many of us have pointed out, if you drive very little you should take regular trips long enough to thoroughly warm up the engine and drive off any moisture, raw gas and other crud.

We go 5000 miles between oil changes and document all work done.

If you can’t take trips out of rown, I suggest changing oil every 6 months or so.

When the dealership gives me their song and dance, I point out that some of their cars sit on the lot for 9 months and do they bring them in for oil changes??

“When the dealership gives me their song and dance, I point out that some of their cars sit on the lot for 9 months and do they bring them in for oil changes??”

good point. This is a case of an unused car (due to illness). I have a charger on the battery, and just changed the oil to be safe, but it had not been used for about a year.


If you think the product you’re putting in your car is anything like what they pump out of the ground, you know precious little about motor oil.

I wouldn’t change oil on a car that is going to sit, but I would put fresh oil in it before I drive it again. It’s important that the oil be able to function when the car is running.