I am sure this has been discussed many times, but what should I put in the 12 valve engine, trans, transfer, and diffs. Is synthetic best? New to diesels any help would be great. Thanks

 

Which religion is the best?
I don't use any synthetics at all.

 

My opinion of the best motor oils are 1- Mobil Delvac 1300 15 w 40, 2- Havoline URSA 15w40, 3- Shell Rotella 15w40. I generally use Wix filters. The 5 speed trans takes a synthetic oil and I usually stay with Dodge oil. I've read some posts that give alternate brands and better sources to buy it from. Maybe they will chime in for you. The axles can use either GL5 oil or synthetic. If you switch oils, make sure you remove the rear hubs and refill the bearing with fresh oil to avoid mixing. If you have a limited slip make sure you use limited slip oil and add the limited slip additive. Good luck


Howard

 

Motor oil- Valvoline Premium Blue 15W40 Recommended by Cummins
Diffs- Amsoil
Auto Trans-Chrysler ATF+3

 

Engine - Mobil Delvac 1 w/ Stratopore Filter
Royal Purple Everywhere else
Fleetguard Filters Used Everywhere

 

Lubrication Engineers bumper to bumper.
Bruce

 

Mobil 1 Delvac for the motor, Redline for the drivetrain (debating on trying Amsoil there).