What is the coldest you've started your car (unassisted for atleast 8 hours of outside temps) with GC? How did the oil and the car do? I'm having second thoughts about running GC this winter just because how thick the stuff gets below zero degrees F! I'm wondering if I would be better off using a high quality 5w-20 for start ups this winter for temps. around 0 degree F. The winters are not really bad around here, maybe a couple weeks in the single digits to a few below 0 F.