infidel

Just see how far you get with Chrysler on any warranty issues if they find out you're using a non API certified oil.
Even if the oil has nothing to do with the problem they will deny warranty.
I'm sure Amsoil's oil quality is comparable to certified oils but just try telling that to a corporation looking for any loophole to get out of paying money out.
No doubt Chrysler has a whole division whose only job is to deny warranties.

I wouldn't use any non certified oil if you expect to use your warranty.
After it's up use whatever you want.

Hodge

I think Amsoil owns Cummins. Or is it Royal Purple? Maybe A owns RP...

supr

To start with, what doies Cummins/Dodge say in their owmers manual? They give a change interval depending on the Generation, and typr of driving, usually between 4-7k miles. They have no rrefrenece as to synthtic for their engines. They do, however, endorse Valvoline 15W-40 CJ (Dino) as their preferred product. this product. last I saw, has the highest (or near so) TBN numbers of any CJ or CI+4. I think you would be hard pressed to di better, but you certainly can spend more money on oil than you need to.
In the tranny, there as specs for that too. In auto's, I think any synthtic of name brand quality will stand up to heat better, which is one thing sythtics do well.
The other area I like synthtics for is in the Diffrential, especially for heavy hauling/towing. RP is mantioned in several posts as one lube that does not destroy you limited slip capabilities.
At the end of the day, whatever meets the specs & schedule specified is adequate for most applications.
If you must get a synthetic oil, at leats go for a blend, as the properties of dino & syn will do better on poundiong surfaces (like valave stems) than stagight synthetic.
At the end of the day, the drive train will outlast the truck, if taken care of,
so, a lot of this discussion is mostly academic

DBLR

All I can say is my oil reports show that even after 10K my oil is still good yet I change it out anyway as by that time it a year old so for me its hard to say its no good when the UOA reports say otherwise.

infidel

Oil analysis said my Delo 400 dino oil was still good to go at 12k miles towing heavy so I figured 10k intervals would be very safe.
Been doing that for over ten years with every oil report coming back fine.
Dino oil quality and properties have changed incredibly in the last few years and make the service intervals Cummins established for the older engines worthless.
3 or 5k oil changes won't hurt anything but are a waste of your time, money and natural resources.

DBLR

infidel,

I agree that 3-5K oil change interval (aka OCI) is a waste of resources being the OCI for Dino oil is 7500 miles for severe usage and 15K for normal usage. I have seen UOA show that Group III synthetic oil can go over 10+K for severe usage, longer under normal usage so have a hard time understanding why anyone would throw out good oil that only has 3-5k on it.