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
There is not much difference in a used oil analysis between 15k oil at a year and 15k oil at 6 months. The detergents and other compounds in the oil is slightly less, but still well within spec. In fact, it would be next to impossible to tell the difference between the two.
Some like to error on the side of caution because they do not know any better, and I get that. If you have never performed a UOA to know exactly how oil holds up, then by all means change it every 6 months if it makes you feel better and is "cheap insurance" to you. I, on the other hand, would rather know and have hard data when making such decisions. I change it once a year because I know there is no significant difference between the two time frames based on UOA's from my own truck and the thousands of 6.7L Cummins engines we perform UOA's on at work.
Some like to error on the side of caution because they do not know any better, and I get that. If you have never performed a UOA to know exactly how oil holds up, then by all means change it every 6 months if it makes you feel better and is "cheap insurance" to you. I, on the other hand, would rather know and have hard data when making such decisions. I change it once a year because I know there is no significant difference between the two time frames based on UOA's from my own truck and the thousands of 6.7L Cummins engines we perform UOA's on at work.
