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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ShinerBock wrote:Makes perfect sense to me.blofgren wrote:You are correct. The time frame of 6 months doesn't matter as long as it is changed with a certain mileage or engine hours. As I stated earlier, no oil analysis would be able to tell the difference between 15k mile oil at 6 months or 15k mile oil at 12 months. The 15k interval with the Cummins is even with non-synthetic 15w40.
It would probably make no difference as long as you aren't exceeding the mileage specifications. I'm not the least bit worried about the 1 year OCI that I have been using for several years now.
Then why the heck does Ram have a 6 mo. OCI on their late model Cummins?
They have "severe" duty maintenance intervals for other things like the tranny and differential. Why wouldn't they recommend 6 mo. OCI's for severe duty and 12 mo. for non-severe?
Ram obviously feels there's something that's degrading the oil over time---something that's not mileage related. Some kind of water, corrosion, or fuel contamination issue?
