Ok, laugh away. My woman's car would not crank today. it was just changed with a garage-cleaner blend of some Pennzoil HM 10w-30 and 10w-30 M1 and ~other~ oils including some GC. I expected it to crank like a 5w oil, but with a good battery it would not crank at all. A clutch-popping pushstart with a downhill assist is what it took to spin the engine. It seems like when you mix, you get whatever the highest W winter rating the oil is made of, in the mixed product. I am going out to change to BC 5w-40 right now. I will sample the expelled oil and see how thick it is in the cold. Maybe additive clash took away the cold winter rating.