The owner's manual for our 2002 Chrysler 300M specifies 3000mile/3month oil changes for "severe use" (which includes the short trips that our car makes most of the time). We bought the car new and have stuck to that schedule pretty well. The owner's manual for our 2008 Vibe specifies 5000mile/3month oil changes. We bought the car a few months ago from a friend, who followed the shop's recommendations. With modern synthetic (or part-synthetic) lubricants, do we still need to follow these schedules? I know that many newer cars have much longer oil-change intervals, but is this as much because of changes in engine design as because of improvements in the lubricants? Perce

Modern synthetic oils can run much longer before the base oils break down. However, they can't keep any more blowby debris in solution than old oils, and the viscosity improvers don't last any longer. So... whether you can get away with extended oil change intervals with modern synthetics on older engines depends entirely on what characteristic of the oil is limiting the oil lifespan. And you can't really tell that without doing regular oil testing on a constant basis. This is very expensive, much more so than just changing your oil a lot. So, the answer is that it depends. But I'll say that I have been using synthetic oils with 3,000 mile changes for the past 20 years and I have 410,000 miles on my engine with cams that still look brand new. Maybe it would have been just as good if I'd changed it ever 6,000 miles, but then again maybe it wouldn't have been. --scott

Oil change intervals?

Apr 13, 2016 23 Replies

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Andy K 10 years ago

I agree with you.

Severe driving would include things like lots of towing, driving thru sandstorms etc.

Andy

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Andy K 10 years ago

Based on lots of experience, Ford is in the top 2 worst cars in terms of reliability.

So it makes sense they would say any driving is severe. They know their vehicles do not last long.

Andy

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thekmanrocks 10 years ago

Andy K:

Severe duty: Towing at least a dozen 10-15m long boats boats per week.

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Andy K 10 years ago

Sounds severe.

Andy

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