Assuming that all of the oils in the poll are Mobil1 Full Synthetic, which viscosity would you ideally run in your car year-round?

 

5w30!!!

 

I've dipped down to the 5W-20 myself but it gets cold up here (will be 0 next week) and it seems like my car loves it (thin oil), but hey I'm a sheetmagnet what can I say.

 

0W-30 cst
-20 C 1998.4
0 C 428.3
20 C 135.3
40 C 56.0
100 C 10.3
130 C 6.0

5W-30 cst
-20 C 2225.1
0 C 452.9
20 C 138.3
40 C 56.0
100 C 10.0
130 C5.8

These are cst ratings at each given temperature (both are virgin Mobil1 Synthetic). The 0W-30 is thinner at the coldest temperatures, but is actually slightly thicker than the 5W-30 in the normal operating range, and even the overheat range. Sooooo... can we assume that the 0W-30 is better suited for most conditions, hot and cold?

 

You coulsd assume that based on the data provided, but without and actual comparison...who knows! I don't have to worry about -20° temperatures living in Texas so 5w30 for me works just great.

 

... except for maybe next week! lol - Anyway my point was that assuming 0W-30 and 5W-30 cost the same, the 0W-30 would be the better pick regardless of where you live because it protects better on a cold start, and holds it's "30-weight" viscosity better when hot.

 

5w30 for me. Wootzors....its all I've ever used. It is also what is recommended in my cars manual as well.

 

if my car has 50,000 on it, is it better to use 5w-30 or 10w-30?

 

5w30

 

What about the oil im running??? Its like 6 bucks a quart....castrol gtx 5w-50....