Inver Grove Toyota Service

Paul Brand
Star Tribune
08/26/10

Synthetic oil still has to be changed

Q. I just purchased a vehicle with 203,000 miles. It's in good shape, and I foresee driving it for
the next decade with good maintenance.

I have been told that I can change to synthetic oil, and using special filters I would never have to
change the oil again, unless it became contaminated and the filter didn't seem to be taking care of
it. I was told this is because synthetic oil will never break down at normal or even high operating
temperatures. So I could just change the filter every 3,000 miles or three months and replace the
oil lost in the filter.

My mechanic says that even with synthetic oil, I should change it every 5,000 to 6,000 miles. He says he's seen cars where the owners changed only the filter, and inevitably the engines are coated with sludge inside. What do you recommend I do?

A. Listen to your mechanic. Change the engine oil and filter -- regardless of the type of oil
you choose to use -- every 4,000 to 5,000 miles. With your estimated 7,000 to 10,000 miles per
year, that would be twice a year at most. Even at $50 per synthetic oil change, why would you not
change oil and filter?

Every automaker's recommended maintenance program includes regular oil and filter changes.
Every automotive warranty requires following the carmaker's maintenance schedule. And the
bottom line, of course, is that it's your name on the title and registration.

Yes, synthetic oils are better at maintaining viscosity than petroleum oils, but they contain the
same additives to protect against corrosion, foaming, wear, etc., including additives that work as
dispersants to keep contaminants suspended in the oil. Additives are consumable, meaning they're
used up over the service life of the lubricant. Motor vehicle engines use full-flow oil filters that
filter every drop of oil before it is pumped into the engine. These filters trap particles down to 10
to 15 microns. Any finer filtration could restrict oil flow in cold conditions. That's why you need
to change the oil and filter.

No matter the type of lubricant -- petroleum or synthetic -- soluble contaminants like combustion
acids, water and fuel can remain in the oil until it is changed. A bypass filtration system that
pumps some of the oil through a much finer filter might justify longer intervals but wouldn't
eliminate the need to change oil.

Modern automotive engines and lubricants are far better than even those of 10 to 20 years ago.
But they still require regular maintenance -- which is your responsibility. You make the decision.

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