How often should you get an oil change?

Of course, driving conditions are seldom ideal. Lots of idling, stop-and-go traffic, extremely hot or cold weather, humidity and towing can all decrease the lifespan of engine oil. Plus, every car is a little different. The interval that is perfectly fine for one car could be way too long for another. So in reality, very few drivers will go 25,000 miles without an oil change, even if they spring for high-grade synthetic oil. And most of them shouldn't, although some can go 10,000 without a problem.

And yet most people still aim for 3,000-mile changes, perhaps because they don't know it's excessive, or perhaps because they adhere to an extreme better-safe-than-sorry principle. The result is millions of extra dollars wasted on oil changes and millions of extra gallons of oil potentially polluting the environment.

The best advice, then? Ignore the oil industry and go by your car's user manual, which will probably advise an interval of 5,000 miles or more. You'll save some money -- and possibly keep the world a little greener in the process.