Recommended oil and filter changeout intervals have increased significantly over the past 10 years or so -- to as infrequently as once every 8,000 (or even 10,000 miles or more) in the case of a few vehicles -- vs. once every three months and 3,000 miles or so.

These extended service intervals concern some drivers who worry they may be harming their vehicles or at least pushing them toward a premature date with the crusher.

But in general, there's nothing to worry about.

The reason for the increase in recommended service intervals is twofold. One: Modern engines operate with ever-increasing efficiency -- which has reduced the rate at which oil becomes fouled with harmful byproducts of internal combustion, such as water and unburned fuel. Two: Today's oils are formulated to last much longer -- with better additive packages that extend their service life significantly. This is especially true of synthetic oils -- which many automakers (Mercedes, Chevrolet, Cadillac, etc.) now use in several of their models and which they recommend be used exclusively for best mileage, performance and engine longevity.

For consumers, having to change the oil and filter less often equals less money spent on basic maintenance as well as fewer trips to the dealership for service.

This is good news -- but a few cautionary notes should be remembered:

One, the "maximum recommended interval" listed in your owner's manual (and talked up by the salesman) is just that -- the listed mileage/time interval is the longest you should ever let your vehicle go in between oil and filter changes. Extending the interval beyond the recommended maximum can be penny-wise, but often pound-foolish. "Saving" $40 on a skipped oil change isn't much consolation when you get slapped with a $800 repair down the road caused by sludge buildup inside the engine. The emissions control systems of modern engines can be very sensitive to the buildup of crud -- for example, the crankcase ventilation system. (Several new cars and trucks are even equipped with onboard electronic oil life monitors that alert the driver when it's time for a change -- which is sometimes well before the scheduled date in the manual.)

Two, you may still need to change your vehicle's oil and filter more often if the type of driving you do falls under the "severe service" or "heavy duty" service schedule listed in the owner's manual. Many people don't realize that today's routine stop-and-go commuting and city-type driving counts as "severe service" -- requiring more frequent oil and filter changes. If you use your car for short trips and rarely drive on the highway at steady state speeds that also may qualify for the shorter changeout intervals.

Three, you must use the specified grade/type of oil. Automakers are very specific about the weight/grade and additive packages you should use in your engine. Failure to use the correct type of oil can lead to poor performance, possibly engine damage -- and could void the terms of your new car warranty. Your owner's manual will contain the information you need to know under "maintenance" -- including specifics about weight, API service ratings and so on.

Finally, check the oil level periodically. This is especially important today, in our self-service world and when you might go six months or more without lifting the hood. All engines -- even those in $100,000 luxury cars -- use some oil as part of normal operation. So the level will fall over time -- and if you let it go too far without a top-off, you could have a very bad day indeed. Few things are more miserable than ruining a $4,000 engine because you failed to add a couple quarts of $2.50 Pennzoil.