Folks here clearly not used to looking at a full-blown performance vehicle (Ferrari) with a 60 grade. These kind of oils typically shear down somewhat quickly from the UOAs I've seen posted. NOT a '99 Camry driven to the store with ST 5W30 

He lives in Sarasota Florida, which is experiencing some cooler weather at the moment but overall it’s not had sustained cold temperatures enough to make any difference in fuel consumptionI've never seen MPG change in old oil vs new oil in any of my vehicles. However I do see a drop in MPG in cold weather in all my vehicles. Could this be what you are seeing?
You should calculate your fuel mileage by hand, and do it after a full tank of consumption. In every car I've checked, the trip computer calculations don't match reality - and by a greater amount than the fuel mileage differences you claim.I love the trip gauge that resets with each start of the engine.
Shouldn’t you be getting better MPG with the type of weather you are having now since it’s really not anywhere near what most people would consider cold and you also don’t need to use the AC like you would in the summer?Right now we have 40-50 degree nights and 60-70 degree days. And yes, the MPG overall is less than mid-summer. Regardless there has been, over the years, this trend in my "regular" cars and trucks just after an oil change. In these cases the slight drop in viscosity grade (if at all) would probably play a small role. I think there is something else going on. My routes are very repetitive. Just after this recent oil change in my GMC Yukon I am suddenly getting a solid 1 MPG less. I was getting 19-20 and now getting 18-19 MPG. And I am one of those guys who follow this sort of thing. I love the trip gauge that resets with each start of the engine. I have a second gauge I reset when I fuel up and a third one that I reset after an oil change. I know, anal but it's me.
Ali
I think all A/C units today are variable vane and always on. Here the humidity is always so high the vehicle would fog up inside if the A/C was totally off.Shouldn’t you be getting better MPG with the type of weather you are having now since it’s really not anywhere near what most people would consider cold and you also don’t need to use the AC like you would in the summer?
Exactly. It's called "winter blend." That there petrol simply has less energy vs the rest of the yr.I've never seen MPG change in old oil vs new oil in any of my vehicles. However I do see a drop in MPG in cold weather in all my vehicles. Could this be what you are seeing?
Yes and add to this the reservation sells 87 octane non ethanol gas. I constantly get 2 - 3 MPG (depending on the vehicle) better gas mileage over the10% ethanol gas.Exactly. It's called "winter blend." That there petrol simply has less energy vs the rest of the yr.
The AC in my 2018 Corvette and my Civic only comes on when I activate it. I know this because you can see a pretty noticeable MPG drop in both cars with AC on, so I don’t use it oftenI think all A/C units today are variable vane and always on. Here the humidity is always so high the vehicle would fog up inside if the A/C was totally off.