Motor Oil Change Questions

Arthur S

Senior HTF Member
Jul 2, 1999
We have a car that doesn't get much use. It has only been driven about 400 miles since the last oil change 3 months ago. How long (time wise) can I go before things like sludge or other contaminants become a problem?

Should I switch to synthetic? The car has pretty low milage.

Mort Corey

Supporting Actor
Nov 21, 2003
Most of the contamination will be from water. If the car is driven occasionally where it reaches full operating temperature for a while, the condensation gets burned off. So whether the oil in your car is still viable is subject to a few variables. If you're worried, change insurance if the car's worth anything and you want to keep it.

Synthetic oil, from my understanding, seems to perform best if used initially in a fresh motor. Kind of an expensive alternative in a car that seems to be barely driven.


Bob Graz

Supporting Actor
Sep 26, 2002
You could probably go a year. I personally would change it every 6 months. I wouldn't do it any more frequent than that and I'd use regular oil.


Supporting Actor
Oct 3, 2006
Real Name
From what I've heard, it's probably worth changing it at least once per year regardless of the miles driven. As it was pointed out, its cheap insurance, if nothing else. It's also not a bad idea to start the car drive it at least a little to keep seals lubricated and such. A lot of the guys that buy classic cars seem to think that this can become a big problem if a car sits too long.

As to synthetic oil, it seems to be best reserved for high stress applications, since it's pretty expensive. I use it in my Subaru WRX, which is heavily turbocharged, but I probably wouldn't bother for a normal car. It normally costs me more just for the oil than it would cost me to pay someone else to change it with dinosaur juice.

Todd Hochard

Senior HTF Member
Jan 24, 1999
I have a 1980 Z28 that I've had for 16 years. It doesn't get driven much these days, maybe 1000 miles/year, and I change the oil once or twice a year. I use synthetic, but that's because when I drive the car, I *DRIVE* the car.

The bottom end of the motor is original- born in August 1979- and I still have great compression. It sees some cruising, some 1/4 mile runs, and an occasional high-speed blast- certainly more rigorous than your typical car. Last time I checked the main bearings (during a cam swap in 2001), they were starting to show a slight bit of wear, but nothing extraordinary.

I'd change it once in the spring, and once in the fall, at most, and not worry about it otherwise. When you do drive the car, bring it up to full operating temperature (which occurs about 10 miles *AFTER* the temp gauge is in the normal range), and you'll be fine.


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