At what mileage should I change to synthetic oil in the engine?

 

Some folks will say 10,000( I think the manual does too) while the Cummins website recommends waiting until 20,000. Plenty of people do it at 10,000 though. I've got 16,000 and figure I can wait a few thousand more.

 

Is there a point where it is recommended NOT to change to synthetic? Maybe a stupid question, but just wondering. My truck has 56000 miles on it, next oil change is right around 60,000 miles, and I was considering going to synthetic(probably Amsoil-me and my stepdad are gonna go in on a dealer membership together I think).

 

I changed mine at 6K. I had observed 0 oil consumption since new with the factory oil and could not see any reason to further wear out my engine prior to installing the synthetic. I have 12.5K on this (synthetic) change and have not needed to add oil yet. Mileage is 22+@60mph 19+@70 on freeway.
So far truck exceeds my expectations.

In my opinion if your oil consumption has stabilized prior to the 20K cummins recomendation, switching to synthetics will do no harm. I would not put it in before I was confident that the rings had seated.

jim B

 

What are you waitng on, you haven't done it yet. I did mine at 3250 miles and haven't looked back since. OK, that did mean that it should have taken longer to break in , but I just ran it hard and pulled a TT accross country to break it in.
If you do wait too long thatn yo take the chance of having major oil leaks. That's because the true 100% systh oils will eat thru all of that nasty oil build up of sluge and gunk that has been festering in you engine. Because of this it can cause the seals to leak becasue you have just removed all of that glunk from them. How the upside to going to 100% synth is the engine will love it and run much cooler and easier, usually about 200rpms lower at normal speeds.

Run the 100% synth and feel the force, also make sure you run an oil filter designed for synth oil, not the average off the shelf filter. You can run the MOPAR, its actually a good filter.