It's a message that has been steered at drivers for years: Change your engine oil every 3,000 miles. Mechanics say you could be damaging your engine if you don't. Yet Consumer Reports says it's a waste of money.

So who is right?

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Severe conditions necessitate more frequent oil changes

To reconcile the varying points of view, you've got to consult your owner's manual and use a little bit of common sense. Most owner's manuals for newer vehicles will tell you it's acceptable to go 5,000 miles between oil changes under normal conditions. But you should drop to 3,000 miles if you drive under severe conditions.

What exactly are severe conditions?

One oil change technician I spoke to said that "jack rabbit" stops and starts — the kind people tend to do when racing from traffic light to traffic light — are a prime example. An AAA Auto Club spokesman I heard from cited other factors, including extreme heat and using your vehicle to tow others. Other factors might include driving in very dusty parts of the country or frequently driving at high altitudes.

If you're just driving back and forth to work during the week, and to soccer fields and baseball games during the weekend, then there's really no sense in changing your oil every 3,000 miles. A couple of years, a Consumer Reports study put the brakes on the myth of the 3,000-mile oil change. They found no noticeable difference in engine protection whether you changed the oil every 3,000 or 7,500 miles.

Ultimately, this one has to be a personal decision. Maybe you're comfortable changing every 3,000 miles and think 7,500 is too long to wait. Then why not split the difference and do it every 5,000 or so miles? You'll be saving about a third by going those extra miles between oil changes.

Experts tell me a $20 oil change is the best preventative maintenance you can do. So the interval is really up to you as long as you don't exceed what's recommended in your owner's manual.

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