This is what I believe. I have a 2014 and change oil myself at 5000-6000 miles. When I first heard of the oil spec change, I went to the dealership and verified it. I had been using Quaker Ultimate Durability with 1qt Lucas. Now I'm using Rotella with 1Qt Lucas. Fuel mileage has gone down...
I've noticed large variations in my mileage for no apparent reason. The answer lies somewhere among outdoor temperature, humidity and regeneration cycles. Best mileage I ever got was 32 avg on I 40 in the mountains around Asheville (only once). Mountains at 70 best?? Sometimes it drops to as...