Questions and Answers

Why 12,000 miles or 12 months? Q. Hi, Why do car maintenance schedules say "every 12000 miles or 12 months which ever comes first"?If a car sits in a garage most of the time with very little driving, surely there isn't much point in oil changes when the oil isn't being worn. Or does time and air have an effect on oil? Thanks...

A. Have you ever walked out on a cool morning and stop to see the birds singing, the bees buzzing and dew on the grass? I think we all have at one time or another. Or at least we should.

Anyway, that dew that forms on the grass can also form inside the crankcase of an engine. This would cause water to collect in the oil pan and possibly damage the engine. Same with many of the fluids in a car. Oil should be changed, according to the book, every 12 months because it will have gone through three season of dew formation.

Brake fluid it recommended to be changed every tow years because it absorbs moisture directly from the air. The more water brake fluid absorbs, the lower it's efficiency.

Now I'm sure some engineers parked a bunch of cars in different parts of the country and studied this to come up with the time intervals. Personally, I recommend 3 months or 3,000 miles because the intervals in the book are for "normal" service. We in the everyday world subject our cars to what they consider "severe" service.