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I changed my oil 2 weeks ago, and I overfill it a little bit and I was too lazy to drain the oil out again. It is 2-3mm higher that MAX on the dip stick. The car runs fine for 2 weeks and I put about 1000 miles on it already.

The odd thing I notice is that my car actually get better mpg, I get about 37 mpg out of my 5 speed EX with 68000miles, which is 3mpg more than b4 when not overfilled. I drive the car pretty fast, rev to 6800rpm pretty often and bring it up to 100m/h for many times.
And it actaully run a little smoother too.

It is just amazing how that D17 perform, I mean it doesn't have much power, but with 68000 miles, it still run pretty much like it was new. Only engine mod is K&N drop in filter. and get 390miles b4 the light is on.

Can anyone explain this??Or it is something else not related to overfilled oil.

 
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I have heard of people adding half to a full extra quart of oil when they autocross to help with the, for lack of technical terms, "sloshing around" of oil. It helps when racing I guess, but I would be wary of putting any extra in your car for everyday driving. In the long run, this may cause oil leaks due to extra pressure on your seals.

 
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+3mpg could be caused by a hundred different things. A few mm's on the dipstick could be caused by an unlevel car, checking the oil when it's not at operating temp, etc. I wouldn't lose any sleep.

 
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wtf ****, how in the hell this could ever happened??