Rotella 5w40 in summer 2007 Duramax....shearing??

Messages
286
Location
Bay City Michigan
Owners manual calls for 15w40, above zero. Synthetic 5w40 below zero. Im running CJ-4 rotella 5w40 year round....do you guys think im throwing my money away in the summer time sticking with the 5w40? Do you think the 5w40 synthetic will shear any compared to the rotella 15w40 dino? I can get a pretty good deal on a 10 quart jug of rotella 15w40, but have been using the 5w40. Chime in all!
 
Messages
11,184
Location
Bad Axe, MI
 Originally Posted By: zrxkawboy
 Originally Posted By: Johnny
I would use the 5W-40 year round.
+1
x3,,we have it in some of our DM too year around.
 

dnewton3

Staff member
Messages
8,459
Location
Indianapolis, IN
If you're only doing one OCI/year, then the 5w-40 will be a great all-around performer. If you're running enough miles (or just can't resist the AR OCI approach), then you could use 15w-40 in the summer, and 5w-40 in the winter; saves you a bit of money for the summer sump load. Dmax engines typically don't shear the oil much, if any, at all; moot point in your application.
 
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