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Old 02-25-2013, 06:36 PM   #62
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Join Date: Jul 2004
Location: Markham
Posts: 2,560
I get it now... the lower viscosity allows the oil to leak back past the rings into the crankcase. The high viscosity stuff is just too thick to allow that to happen and it gets burned away ...... Doesn't work if your car is upside down though....

Maybe the lower viscosity helps BMW meet the CAFE requirement
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