Reason for asking: Scored some $10.97 Valvoline MST 5w40 recently, had a bunch of 5w20 Valvoline Synthetic from last year's discount. Based on data sheet it seems like they are 66cst/13cst and 44cst/8cst. So if I mix them 1:1, am I correct that it should come out to around 50cst/10cst? In that case it should be a Xw30 oil for cheap.
Would that make sense? Anything I'm missing? It would be for a warm climate car (90F in the summer high and 45F in the winter low).
Would that make sense? Anything I'm missing? It would be for a warm climate car (90F in the summer high and 45F in the winter low).