I live in the Northeast, and use synthetic 10/30. My car has over 200k miles, runs fine, and starts quickly, even in cold weather. Supposedly, if you park an e28 535i on a slope facing downward, the oil pressure light goes out faster. I've tried this and it seems to be true. I don't know enough about the internals of the engine to explain why. 87 535is 145k This is my first fall/winter with this excellent running car which I purchased in the spring.I am currently using Castrol syntec blend 20/50,I live in northeast New Jersey & the past week or so since the temps in the mornings have been hi 30's lo 40's I've noticed slower,longer crank times & 10 seconds for oil light to go out . This morning was a whopping 15 seconds for oil light to go out !! With temp 50 & over engine cranks & starts instantly & oil light is out after 2 to 3 seconds. What oil to use ???