Steve Schaffer
Senior HTF Member
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- Apr 15, 1999
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- Steve Schaffer
The 7500 mile recommendation was for "normal driving" which is considered to be about 75% highway with relatively few short trips--in other words traveling salesman use. In reality most cars are driven primarily short distances and rarely does the oil get hot enough to burn off moisture condensation. In addition few owners take maintenance requirements seriously enough to actually do them at 7500 miles, usually stretching to 10 or 15k if at all. The result has been class action suits against automakers when engines sludge up.
The temp guage on cars indicates coolant temp, oil takes a lot longer to reach optimum temperatures.
So just because your temp guage gets to normal within a few blocks of driving doesn't mean the oil is hot enough to burn off the moisture that accumulates in the oil. The presence of ethanol in so many fuels means even more moisture in the engine.
Anyone interested in actually keeping a car longer than the typical 2 or 3 year lease contract would be better served by following the "severe service" maintenance schedule which usually does recommend oil changes every 3-4k miles.