quote:Well, the heat will certainly reduce mileage. Also, do you have summer reformulated gas in your area? That will knock your mileage down right there. I've never heard of synthetic making negative impact on mileage when the same viscosity was used. Especially with Mobil 1 since it runs thin (within its rating) anyway.
my mileage has actually decreased. temperatures have been unusually hot here in mi, so there has been lots of a/c on, and i sat for a while at the airport waiting for my wife's flight to arrive, but all my mileage numbers have been down somewhat.