How Often Should You Change Your Oil?

October 26, 2009

Even though the Clunkers for Cash program provided a momentary shot-in-the-arm for the auto industry, the auto market still remains very soft.

Indeed, when polled new-car buyers recently, 100,000 respondents said they planned to keep their cars much longer than they would have normally.


If you're one of those 100,000 new-car buyers or one of the million or so buyers who purchased a new vehicle under the Clunkers for Cash program, the only way that you'll be sure your vehicle remains reliable for a long time is to have it serviced regularly.


For instance, if you normally waited until 8,000 or 10,000 miles to have the oil and filter changed and to have a lube job done, it is a good idea to have that lube, oil and filter change at about 3,000 to 3,500 miles (the auto industry recommends about twice that and many drivers go even further).

Changing the oil and filter every 3,000 to 3,500 miles will result in a cleaner engine and more reliability for you, especially if you are a short-haul driver. To define short-haul here, let's say you drive less than 5 or so miles per day.

This type of driving is slow death for a car. It is true that you are moving your car every day, but you aren't giving it a chance to warm up thoroughly. It takes roughly 10 to 15 miles of driving for your engine and associated systems (ie. Block, pistons, transaxle) to reach their proper operating temperatures.

Oil is dirty stuff

Let's start off this part of the discussion with the admission that even though it may be new and clean, oil is really dirty stuff. If you were to look at a batch of oil under a spectrometer you would see that it is a sea of gums, laqs and waxes. They are part of the oil itself and cannot be refined away. They remain in suspension in the oil. Indeed, oil producers have to introduce cleaners and detergents into their product for it to work correctly at low mileage and lower-than-normal temperature.

Normally, it takes a minimum of about 10 miles for your engine, transaxle and all the associated pieces to warm up enough so that any gums or laqs remain in suspension and so that the detergents in the oil can work. If you don't drive that distance you begin to lay down lacquer deposits that can close off the small cooling galleries in your engine and can cause many problems. And the longer the oil remains in the crankcase, the better the chances are that your engine will build up not only lacquer deposits but also gum deposits that can further harm your engine.

Therefore the best way around this problem, especially if you are a short-haul driver, is to have your oil and filter changed about every 3,000 to 3,500 miles so that the deposits never have a chance to form as the detergents hold them in check. This figure that is not only backed by many longtime mechanics, but also the Car Care Council. Indeed, some further refine this by saying that if you don't drive far or long enough, it's best to have the oil changed every three months.

At the same time, the filter should be changed. This is especially important because engines now are smaller, harder-working and are built with tighter tolerances. They also run lighter weight oil to reduce friction and save fuel, so premium filters are the best replacement option for any vehicles they keep clean oil flowing through the engine.

Oil has many roles

Oil plays a variety of roles in your engine. It is not only the key to proper lubrication, but also to cooling, believe it or not. The oil, as it circulates through the galleries of the engine takes away much of the heat generated by your engine and as it circulates through engine and into the oil pan, it dissipates much of that heat buildup, so it plays a very important role in not only keeping your engine functioning and healthy, but also cool. The filter also helps the cooling process.

And, even at today's pricing for oil which may seem high, changing the five quarts of oil that your engine needs (four for the engine, one for the filter), it is very inexpensive when you think about the consequences of leaving your engine oil unchanged for too long.

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