I'm sure it's been posted, but I couldn't find any info...At what mileage would you suggest switching to a full synthetic motor oil? My truck has 12K on it, is that too soon? I've heard conflicting info but 20K sticks in my mind for some reason Please post up and educate me Thanks!!

 

I have changed all mine out at 10k No problems.
AMSOIL IN EVERYTHING!

 

cummins says on their site- 15,000-20,000 miles depending on your driving (towing,etc)

 

Like RJM222 says, the Cummins site says start at 15 -20 K. The owners manual does not say a specific mileage interval. I started at 3 k. If I had to do it all over again I would have waited until 15 -20 just as the web site states to be on the safe side.

 

I waited until 20K miles on the clock and then changed to Rotella 5W40. First thing I noticed was that the engine now sounds quieter and smoother.

 

An engine wears the same with synthetic or dino. The only difference with a synthetic is better cold flow properties during startup and resistance to burn off (NOACK volatility).

Switch over your truck when you want to. The old wait till xx,xxx is a wives tale that will likely never die.

 

Thanks guys. My truck is due for an oil change in 2500 miles, and I think I'm gonna switch it over.