Engine oil VALVOLINE or Shell

If you want brand recommendation choose Valvoline Extended Protection 5w-20 every 4k miles.

Rotella T5, up to 14k in between changes per oil analysis. Great oil, never had any issues.

Cummins uses Valvoline premium blue.

I've used Rotella T4 15w-40 in my 2008 6.7 Cummins year round in Canada. The ol girl has 700,000km (420,000 freedom units) and she runs like a top.

Similar with my Audi but with Valvoline.

This weekend, the oil that's in it is coming out (it's clean) and Valvoline Restore and Protect is going in. Rationale is there will undoubtedly be deposits on the pistons, in the piston ring grooves and ring lands.

Rotella 5w-40, for no other reason than it is good oil that I can use in every internal combustion engine I own, including wet clutches.

Rotella 15w40 for mine. Never an issue and good oil reports for several hundred thousand miles.

Rotella T6 has been good to me.

Rotella T-Syn is a great oil but for our turbos...i wouldn't recommend it since if any oil gets burnt or makes it way through the rings...the higher amount of ZDDP (zinc) found in the Shell Rotella Synthetic oil will be harmful to your catalytic converter which may cause a failure.