Oil changes

I read that the oil should be changed every 5000 miles

or 6 months which ever come first. Since I only drive about

5000 miles a year the 6 months always comes first. I can see

how the oil wear is a function of the miles but why does it need

changing every 6 months?

thanks, bill

Spring and fall makes sense. One of our cars goes this little and that is what we do. Your owner’s manual will give a time and mileage interval.

If you drive that little, you will likely accumulate sludge in the oil. We advise drivers like you to make one fast highway trip per month for at leat 30 miles.

Cars are like people; with too little exercise they get “bunged” up!

When I was driving my car 5,000 miles per year or less I changed its oil once a year. I never had a problem. The car gets driven more now, and the oil gets changed every 5,000 miles.

As long as, when you drive the vehicle, you drive it long enough to get it fully warmed up (20-30 minutes or so), you should be OK with changing the oil once a year.

If, on the other hand, all of your trips are short (a few miles) every six months might be a better idea.

A low mileage car tends to get more moisture and other by products in it.  Oil is cheap compared to engines.  Your choice.

The recommendation for the 6 month oil change is due to the fact that not everyone knows where the engine is going to be operated, or under what conditions it is going to be exposed to during those 6 months.

If you live in a very humid area, that gets lots of rain (think Everglades or Seattle), or has huge swings in temperature during the day, you have lots of moisture in the air all the time. What happens is that there will be condensation (water) building up inside the engine, and that can get into the oil.

Changing the oil every 6 months limits how much water might get into the engine, and stay in the engine oil. Of course, driving the car and getting the engine oil good and hot will evaporate some, if not all, of the water in the oil.

At the same time, during the combustion process, there are acids that are created.
Engine oil pulls the acids off of the cylinder walls and the pistons, and does its best to neutralize the acid. Eventually, if there’s enough acid in the oil, it can’t neutralize all of it, so you have to change the oil.

So there’s the two major reasons why oil should be changed on a time limit instead of a mileage point.


I pretty well agree with the prior statements, however, if you are still in warranty, you will have to stick to the six month maximum change interval.