2020 Cummins 3500 HO oil

[larryq]

I performed the first oil change on my truck today, and hate to poke a snake, but is my new engine a full synthetic a requirement?

had the last 3 gal of Rotella t Dino on the shelf.

I bought t6 Rotella , but should I abort this fill and replace with T6 full synthetic??

still learning again after all these years!

if I run this for 3000 will I still be ok??

 

[AH64ID]

No it’s not a requirement.

The two spec’d oils are a 10w-30 and a 5w-40 synthetic. A 15w-40 should be just fine too, but that’s your call.

 

[sag2]

From TSB 09-011-20

CAUTION! 15W40
grade oil CAN NOT be used in any 2019 model year or newer 6.7L
equipped vehicles due to the new designed valve train of this engine. If this oil is
used, it will cause deposits to form in the Hydraulic Valve Lash Adjusters leading
to undesirable noise, and/or engine damage.

 

[TFucili]

sag2, can you post the TSB? I have a friend with a 2019 who insists on 15W40.

 

[JR]

I find it really hard to believe 15w40 will cause engine damage in all but the most extreme environments but 5w40 will not. It just doesn't make sense.

 

[larryq]

I find it really hard to believe 15w40 will cause engine damage in all but the most extreme environments but 5w40 will not. It just doesn't make sense.

thanks!

just had the oil changed back to T6 synthetic

 

[Jim W]

JR, I can see the reason for the 5W40 oil requirements in the newer engines. 1). The 2019 and up no longer have the mechanical lifters instead they have gone to hydraulic lifters. I believe this necessitates a thinner oil to flow thu the valve train. 2). Another reason if someone had a valve train failure during the warranty period and it was proved the end user used 15W40 oil. FCA could deny the warranty on the engine thus saving FCA $$$$.
Just saving that this could be why the TSB was issued.

 

[Cummins12V98]

I know different animal. Bought 99 Tahoe 350 with 150k. Now has 235k always used AMZ/OIL 15/40 Diesel and Marine. Lifters NEVER have ticked on startup.