5W40 or 15W40 in 6.7 CTD?
So the owner's manual in my 2015 Ram says to use 15W40 oil in the 6.7 Cummins diesel, unless the temp is going to routinely be below 0*, in which case you should use 5W40. Here on Long Island, the ...
Forum Discussion
FishOnOne wrote:
For '19-'20 6.7 Cummins with the hydraulic lifters require 10W30 or 5W40 oils and have moved away from 15W40 oils. Some who have ran 15W40 in these trucks have reported rattling or knocking noises.
I haven't heard about knocking or rattling noises on a new 6.7L due to using 15w40. Although, it would have to be pretty pronounced since the 6.7L is a fairly loud engine and 15w40 has the same viscosity grade as 5w40 at operating temp.
Most engine manufacturers are going to lighter engine oils due to fuel economy concerns. The hydronic lifters may have something to do with as well, but the main reasons for this shift is likely due to the upcoming CAFE fuel economy standards that include all classes into the average instead of just class 1-2A. Every little bit counts and even small gains with keep them from paying millions in fines.
