Jeepman71

I have 116K on my 6.7. I am thinking about going to synthetic oil. Good choice or will I be better off sticking to dino or a blend?

Jim W

Have you read the owners manual? In the manual it states to use full synthetic oil during the winter months 5W-40 so you can also use this in the summer months also. Several owners of diesel truck that are on Turbo Diesel Register use synthetic oil year around with no adverse affects.

In fact Cummins ships the engine from the factory with 5W-40 synthetic oil. This was stated to me on a factory tour in June 2013.

Jim W.

Fiftygrit

I change my oil and filter every 6 to 8 thous, miles twice a year so I went back to the dino oil, both the synthetic and dino oil I use were Rotella. I really didnt notice any differance, cheer`s

mega-engr

I have less than 25K miles on mine and have been using the full synthetic Rotella T6 at every change at about 5K intervals.

Dodgetracker

It wont hurt the engine. It (synthetic) costs more so if you are going to run extended OCI then it will be worth it. As long as it is a proper spec'd oil you will be fine, be it dino or synthetic oil. I personally just went the opposite way, I ran Mobil 1 5w40 for 6 of the 7 years I've had the truck, and just put in Mobil Delvac 15w40. You will be fine with either. Best to you.

Jeepman71

Thanks for the replys. I usually run 3 to 4 thousand OCI because I don't put alot of miles on. I use this truck to pull my fifth wheel but it is also my daily driver. I like the idea of the better oil for the grunt work but it seems a waste for the daily driver part.

Dodgetracker

With those kind of miles, price-wise you would be better off sticking with Dino oil. Valvoline, Mobil, DELO, Rotella, Heck even good service from Supertech oil from Wal-Mart has been had, your choice. Oil choices on the forums are a heated debate as to which one is best, But all have come back with good results from oil samples. As a better price point you might want to go out to between 5000-7500 miles on your OCI's. If you wanted the Syns then anyone of the above mentioned brands will serve you well also (Except for Supertech). Best to you.