Mobil 1 GRAY cap

[blowndodge]

I'd go ahead and put the either the Mobil 1 or Rotella syn 5/40 for now. It takes about twice the temp to burn down synthetic oil as compared to non synthetics. I belief that my next change will be Rotella because the dirt suspension requirements of a diesel (read, far dirtier on the motor oil than gas engines) is higher. In other words diesel is way harder on motor oil than gas engines; way harder. In fact I know of a lot of diesel truck owners that have put a "pre-oiler" on their engines to start the oil pump before the engine is started.. Most of engine wear is due to "dry starts". Oil in the pan instead of the upper end. A lower bottom number like 5/40wt will pump through the engine quicker on start up than heavier oil.

I've read lots of owners complaining on how loud their Nomads are a first start up. Something to think about???

Another thing about oil. Did you know that most high performance motorcycles don't recommend 20/50 oil? Know why? At the rpms they turn the oil thickness starts converting to parasitic losses. It actually will run hotter than 10/40.

So I'd say if you have synthetic non friction reducing oil, 10/40 would be more than fine.

Oil manufacturers started making the thick oil 50wt and 60wt a long time ago for older big engines that had a tendency to burn oil as it worked its way past the rings. Usually this oil found homes in old agricultural engines. Todays modern engines are so tight in their tolerances that thiner oil is fine and usually desireable because of some parasitic losses as mentioned above. Notice the 0/30 wt. oil that come standard in a lot of newer cars now.

Try both Mobil 1 and Rotella and the one that keeps your engine the quietest would be the one to use since both are excellent oils.