I know Cummins recommends 15w40, but I'm switching to synthetic in the new truck and am going to run the 5w40 Delvac. What's everyone thoughts about the 5w40 grade vs the 15w40? Any ill effects? I usually run Delo 400, but since its not available in the old formula, I don't want the new formula because of the stuff/heard about the new formula and premature bearing wear. The Delvac Mobil 1 is CI-4 rated still. Thanks

Tye

 

Well I run Amsoil 5w30 HDD oil in my 2006 and so far I've not had any problems and got a small increase in mpg and I like the better cold weather starting. FYI, Dodge has approved the use of 5w40 synthetic oil in the 2006 engine as listed in the owners manual. I've used Delvac oil before and its a lot better oil then Rotella IMHO.

 

Delvac 1 is one of the best oils you can buy.

 

I run the Mobile 1 Fully Synthetic 5w40 for diesel trucks in mine.

 

Buckshot,where did you find the "old" oil?

 

My understanding is that is just relabeled Delvac 1?

 

It's just what are oil supplier here @ work is giving us.

 

Thanks but here in the Bay Area I can only find the new stuff.All the usual suspects,wally world,kragens,napa,autozone,etc.