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 ...
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Thanks and know that chart but it is not the hot end that I’m most interested in.
Film strength is the biggest component specification am in interested in.
As I believe in the articles over many decades referencing that most of engine wear is due to dry starts. Mostly after extended times off, like over night or a few days.
Too many will just shut off their ICE after driving HARD. I allow mine to cool down before shutting down after driving hard. Around town, sure just shut it off, as my ICE doesn’t get up there in temp just driving around town.
Which reminds me...time to replace the severe duty fan clutch, as it doesn’t couple as high as it used to. Know because it doesn’t ROAR anymore.
Am after the highest film strength keeping as much of an oil film as possible and believe higher viscosity of the lower number helps solve that issue.
Film strength is the biggest component specification am in interested in.
As I believe in the articles over many decades referencing that most of engine wear is due to dry starts. Mostly after extended times off, like over night or a few days.
Too many will just shut off their ICE after driving HARD. I allow mine to cool down before shutting down after driving hard. Around town, sure just shut it off, as my ICE doesn’t get up there in temp just driving around town.
Which reminds me...time to replace the severe duty fan clutch, as it doesn’t couple as high as it used to. Know because it doesn’t ROAR anymore.
Am after the highest film strength keeping as much of an oil film as possible and believe higher viscosity of the lower number helps solve that issue.
ShinerBock wrote:BenK wrote:
IMHO...depends on how hard you plan to drive it...
I'd go higher viscosity
Both have the same viscosity grade of 40 at operating temp so they are about the same when driven hard with 15w40 having the slight edge. It is their cold temp viscosity grade that is different which mainly only comes into play when the oil temp is below 30F. One has a cold viscosity grade of 5W and the other 15W.
Snip....
