Hello everyone, I'm coming up on 30K on my truck and was wondering it that was long enough to safely start with a full synthetic motor oil (amsoil). I have only about 300 miles of towing approx. 6K trailer. Or should I wait another 5or10K.

thanks for the input.

Jamie

 

Cummins recommends 20,000 miles. That's when I changed. Some guys do it earlier but you've waited long enough.

 

that's what I thought. doesn't hurt to make sure though. thanks

Jamie

 

I switched at 8k miles, no problems at all. I seriously doubt you could find any evidence of someones engine going south because they switched to synthetic before 20k miles, but if thats whats Cummins says then they must have their reasons. Good luck.

 

I switched at 3750. Of course i switched all fluids at that point.

 

I just put $11000 in my engine and I went back the synthetics at the first 5000 mile change.

 

FROM THE CUMMINS FAQ PAGE:

" Is it OK to use synthetic oil with my Cummins engine?
Cummins recommends that you not use synthetic motor oil during the break-in period of 5000-20,000 miles, based on the type of driving, to allow proper seating of the piston rings. Beyond that mileage it is OK to use synthetic oil. "


I changed mine over at 7000 miles and have had no problems at all!

 

Have you seen any mpg increase yet?

 

At the same time I changed over to synthetics I put on 315's, and hung a Frt Brush guard on the truck. So, there's conflicting items going on.

THis past weekend on trip from Ft Hood to Freer, TX I got 315miles out of 15.3 gallons = 20.58 mpg at 65-68mph (1800-1900 rpms. On the way back I got 19.5....but was going 70-72mph (1900-2000rpms)