Whatever the summer choice is, if you live in snow states that go sub zero there is a huge benefit from using the 0 winter rated oil. Whether you just stay with that or not through the year is an individual choice, but watch the youtubes out there on cold flow oil tests. On viscosity charts it usually only shows a -5 benefit from 0 to 5 winter rating, but I believe that to be very short sided. the benefit imo is at least -15f. So using a 0 winter rated oil buys you -15 in the bank. Want even more int he bank, look at the heaby pao/ester formulas.