2010 2.5 premium CVT here, we usually get 30-32 mpg when the air temperature is above 40 F. Lately here in southeast Idaho it has been blow zero at night and teens during the day, my mileage is around 22-23 mpg! Anyone have suggestions on possible lube changes in differentials? I have Subaru change the oil and they use Subaru 5-30W, and I never go above 70 mph and don't have a lead foot either, thanks!