I hope I am in the correct forum because the HD trucks did not get updated until the 2020 model year. It is the 6.0 L gas engine.

Anyway, my owner manual says to use 0W20 synthetic motor oil. The cap on the oil fill port says 5W30. I always put 5W30 in my Corvette engines so I'm not really sure which one I should use. I tow a heavy fifth wheel RV for a few hours each month.

Does anyone know which is correct?

 

Hello. I think if there are high loads then it is better to use 5W30.

 

I would contact your dealer and have vin # handy