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**Dolebludger** · 07-05-2008

I will tell you what the techs said, but that doesn't mean I understand it. They said that the oil, whether synthetic or not, accumulates some "blow by" gasoline from the combustion chamber, regardless of how new and "tight" the pistons and rings fit in the cylinders. This gasoline (or diesel fuel, if that be the case) accumulates more and more in the oil with mileage, regardless of type, and reduces its lubricating ability.

I will confess that the topic of this discussion was "how to get your engine to last 300,000 miles", so "abundance of caution" was followed in the advice given. Probably, an owner who wants to trade in his car at 60K to 75K miles or so could go with the owners manual high mileage oil change intervals with no problems at all.

I frankly don't know how long I will keep my cars. That all depends on how well they age. But on the chance that one or more may be a long term "keeper" I change at 5K to 7K miles, regardless of longer interval in the owners' manual.

07-05-2008	#16 (permalink)
Dolebludger Elite SLK World Member Join Date: Feb 2008 Location: Yukon, OK Vehicle: '07 SLK 280; '04 C 320, '01 Honda S 2000, '98 Ford Ranger truck. Posts: 574 Country: Thanks: 41 Thanked 81 Times in 54 Posts	I will tell you what the techs said, but that doesn't mean I understand it. They said that the oil, whether synthetic or not, accumulates some "blow by" gasoline from the combustion chamber, regardless of how new and "tight" the pistons and rings fit in the cylinders. This gasoline (or diesel fuel, if that be the case) accumulates more and more in the oil with mileage, regardless of type, and reduces its lubricating ability. I will confess that the topic of this discussion was "how to get your engine to last 300,000 miles", so "abundance of caution" was followed in the advice given. Probably, an owner who wants to trade in his car at 60K to 75K miles or so could go with the owners manual high mileage oil change intervals with no problems at all. I frankly don't know how long I will keep my cars. That all depends on how well they age. But on the chance that one or more may be a long term "keeper" I change at 5K to 7K miles, regardless of longer interval in the owners' manual. __________________ The SLK -- What the SL was supposed to be.