Valvoline 20W 40?
 

Should I put valvoline 2040 in it durring winter or summer, It seems to me I should run heavier weight in the summer but some people in the oil thred seem to think differently, Im a fan of castrol gtx because it doesnt break down very quickly, so either castrol 20 50 or valvo 20 40 is goin in next change im just not sure weather or not to do it durring winter

I am wondering the same thing. 20w50 seems awful htick to me for the winter. It's getting down in the teens already where I live. let me know what you find out.

mazda reccomends 10w40 for the winter.

Tonto no like 20-50W for winter.
Thick like buffalo hide.

That's what I thought. I may be new to working on rotors but I know that's some damn thick oil to run in Winter! Summer too but given the design of the rotor I can understand.

i heard mazda recommended 20 50 but i could be wrong. I use it in my 79 and TII but warm that puppy up before u drive it. And it is harder to start. I m going to 10 40 in the winter 20 50 in the summer