We have just purchased a new(to us) 2007 Ram 3500 with the 6.7. It has 8000km(5000 miles) on it and I'm wondering if anybody out there has used synthetic oil in a similar motor? Being under warrenty is a concern as the oil has to meet Dodge specs. This truck also has the 6sp auto and has anybody used synthetic oil in the tranny? One other quest, we had a K&N in our older diesel 1-ton and liked that. Any recommendations there?? Looking forward to your recommendations..RMK

 

I moved this question to the Cummins Diesel section for a better response. Originally posted in 3rd Gen. section...

 

I started using synthetic oil at 10,000 miles. I have heard different ideas about when to start, I tow heavy alot!! So I decided to make the switch. I am using Guardol 15w- 40 full synthetic. The only thing that you need to look for is that the oil you choose is API CJ4 and it's low ash...
Good luck. I havent tried synthetic in the trans. But I will be doing the diffs soon.

 

i started synthetic in mine at 15000 miles, if you are worried about warranty you can go with the Valvoline premium blue extreme. the Valvoline premium blue non synthetic is what is shipped in the engines from thr factory.

 

Because it is a 6.7 you need to use low-ash fluids.

 

Amsoil products and warranty can't be beat.