whomikedao

Maybe it's a coincidence, but ever since I switched to the AMSoil Signature Oil I've been getting pretty bad mileage. I thought I might have over-filled it and I did so I took some out and when I checked the oil levels before starting it, it was in between L and H. Checked after warmed up and it's right on H if I remember from last month.

I've been changing the way I drive and drove more grandma-like.
-Changed gears at 3-3.5k and let it coast like I always do.
-Let it coast in gear long.
-Either Chevron 93 or Shell 93
-Alignment done

Is there anything else that affects gas mileage? VA? Differential?

SheDrivesIt

Winter formula fuels and cold temperatures can be big factors. Low tire pressure due to reduced air temperatures can factor in too.

zeroptzero

Definitely this ^ . You could lose up to 25% fuel economy in cold weather regions. Not sure where the OP is located.

Differences in oil might account for a max of 2% if you went from a 20 weight up to a 30 weight, and even that might be too high of an estimate. I don't think oil is the main issue here unless you jumped up a couple grades of oil. If your old oil was Mobil1, you might have gained some viscosity going to Amsoil as Mobil1 tends to formulate their oils on the thinner side of each grade/spec. It could account for a small decrease in fuel economy but it would be hard to document IMO.

whomikedao

Oh that could possibly be why. How effective would valve adjustments take on fuel economy? I should probably check that soon