Thread: Mmo
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Old 12-12-2011, 11:08 PM   #19
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Join Date: Dec 2005
Location: Brookline, MA
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1995 SL2
Default Re: Mmo

Originally Posted by td1238 View Post
It'd be interesting to see the pistons from that Saturn engine above that was run on synthetic.
Unfortunately, I didn't take any pictures of the pistons, but other than some carbon on the top, they were in great shape (no scoring on the skirts and clean, inside and out). There was a tiny bit of carbon/build-up in the oil ring grooves, but the rings were all free and not at all gummed up. Oil consumption was about 1 quart every 3-4k miles, which is not excessive even for a new car (most if not all of that can be explained by the cam cover leak).

The BMW engine is a worst-case scenario: conventional oil and extended drain intervals (well over the recommended 3k-6k miles). If conventional oil is changed every 3k miles, it will never look anything like that, but it will not be as clean as with synthetic, even with much longer intervals.

These are the pistons from a lower-mileage gen3 engine (around 70k miles). They have already been mildly cleaned (brake cleaner and rags to get off anything loose). The pistons from the engine above were MUCH cleaner than these: they had none of the carbon/deposit build up on the sides--other than the ring groves and tops, they were like new pistons, dipped in oil. (I took the rods from these to use with my gen3 version sealed power pistons.):

Last edited by PlasticCarsRock; 12-12-2011 at 11:19 PM.
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