Eliot Silverman

Eliot Silverman

Thursday, March 29, 2012

If I use regular oil (non synthetic) how often should I change my engine oil?

Until recently manufacturers and independent repair shops said you should change your oil and filter every 3,000 miles or 3 months whichever comes first.  Recently, manufacturers have stated that the oil should be changed every 7500 miles under “Normal” conditions.

This “Normal” condition statement, in my mind, is a winnie clause.  I say this because of how manufacturers define ‘Normal.”  “Normal Conditions:” engine at operating temperature (What does that mean?) at highway speeds, and in a dust free environment. 

“Severe” condition is defined as: stop and go driving, trips of less than 10 miles, city driving, or extreme heat or cold.

Think about those two conditions…. Where in the USA will you be able to drive in “Normal Conditions?”  I can’t think of any, and for sure NOT in Chicago.

If you drive your car almost anywhere in the USA you will be driving in “Severe” conditions.  Therefore, you should change your oil and filter every 3,000 miles.

In Chicago I recommend you change your oil every 3,000 miles or 3 months. 

Because dirt in your oil can cause severe wear, you are safer changing the oil and filter
too often rather than not often enough.
Your oil is your engine’s cesspool system.  The oil filter stores a limited amount of dirt.  Once you exceed the limit, the oil and dirt bypasses the filter allowing the dirt to cycle throughout your engine.  Nobody knows how much dirt is in the oil, and how quickly it accumulates.  When you get an oil, lube, filter change, mechanics do not inspect the oil filter- we don’t have the equipment to do so, nor would you want to pay for that inspection.  Therefore, we do not know if you really need a filter, or if you waited too long before it was changed.  To prevent severe wear and tear in your engine, you are much better off changing the filter too often rather than not often enough.

Every once in a while I get a car whose oil is rarely changed.  In these cases, the oil has solidified inside the engine.  There are small passageways the oil needs to flow through to properly lubricate your engine.  When the oil solidifies it will not flow through these passageways causing premature engine failure.

Some newer models have a “variable cam shaft.”  Using a variable cam, engineers have been able to increase horse power without increasing the size of your engine.  Oil is used to ‘vary the camshaft.’  If you don’t change your oil often enough, or you use the wrong viscosity oil, the passageways to the variable camshaft ‘plug’ and the shaft doesn’t “Vary.”  This causes the ‘Engine’ light to come on. 

Changing the oil does NOT unplug the passageways.  The only way I know to unplug them is to put a thin metal rod, like a pipe cleaner, through these passageways. Sounds easy, but it is very expensive, and sometimes not even possible.

If you use the proper viscosity oil, and change it on a regular basis, you prevent clogging, and premature engine failure.


  1. To change oil that means renewing your car from carbon deposits.

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  2. Carbon deposits are not removed when you do an oil change. Carbon deposits occur in the intake system, fuel injectors, and can accumulate inside the combustion cylinders.
    To remove carbon deposits you need to do a fuel injection cleaning.

  3. To change oil that means renewing your car from carbon deposits.
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