Mileage drop

[hdmax(mike)]

I installed the Amsoil dual oil filter by pass and 3000 heavy duty oil last Sunday. Now with one tank of diesel used. I see the mileage is down almost 1 mpg.

Weather has been less humid and a little cooler. I drive the same route everyday and I use cruse control most of the time. So I know my driving style hasn`t changed.

Everywhere I`ve read about the 5w30 Amsoil. It stated fuel mileage improvements. WHAT`S THE DEAL?

Has anyone else had this problem?

[86gmc]

Doubt it is the Amsoil causing a drop in MPG. I run Amsoil in mine & maybe a slight increase of 1/10 or 2/10 mpg but definitely not a drop. might be the cooler weather and it will drop some more using the winter diesel fuel soon.

[3176CATPOWER]

Quality of fuel can vary that much,run a few more tanks before getting too concerned.I get very consistant mileage but once in a while it drops for no reason,just changed supplier and looks like it is going to get signifantly better.