Can too much oil, 3 quarts, reduce mileage?

[brpeterson]

I recently had an oil change at a dealer. Then my mileage went down about 3mpg. Usually it goes up a little with a change of the oil. The dip stick reads a little high. Do you think they may have put three quarts in? Would that lower mileage? How could I suck out a little oil if need be?

[Insightful Trekker]

I've done it regularly in over the past 40K miles without any noticeable problem or MPG difference. On my current oil change (yesterday) I went to the extra trouble of precisely filling (with accounting for thermal expansion) and have yet to see a difference. 1 quart overfill (1/2 -3/4" on the stick), possibly.

See the recent thread:

http://www.insightcentral.net/forum/vie ... 98892e1e5f

Tire pressure? Grade of oil? Cooler fall temps?

HTH! :)