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Old 10-08-2008, 11:12 PM   #29 (permalink)
trebuchet03
MechE
 
Join Date: Dec 2007
Location: Bay Area
Posts: 1,151

The Miata - '01 Mazda MX-5 Miata
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Quote:
Originally Posted by Bror Jace View Post
For those of you skimping on oil changes, the coefficient of friction of the oil goes up as contaminants accumulate and the additive package becomes depleted. As friction goes up, heat and drag increases ... reducing efficiency. The pennies you save will cost you over the road.
Yes, friction goes up as contaminates accumulate and additive packages deplete... But to say my long oil change interval = accumulated bits and depleted additive packages is a fallacy.

Every oil change, I send a sample to a lab for testing. I can tell you, with certainty, my contaminates are low*, insolubles are low (filter is filtering ), viscosity is within acceptable limits, and TBN has always been above 6.0

*except for copper - 2000 VW 2.0 engine had their piston rings installed upside down from the factory (piston ring mfr started stamping their label on the bottom rather than the top as they did prior: as a result, a chamfer isn't where it's supposed to be) - so occasionally copper wear is a little higher than it should be, but not by much.

My best tank to date was on oil with over 9K miles (that's conventional oil too ). Yes, that's anecdotal - I'm just throwing that out there
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