Bough the truck in July of 17'. All OCI's are at 5K & for the first 50K miles I ran T5 15w40 then switched to T6 15w40. This truck is worked, tows a 28' race trailer @ just shy of 13K lbs when loaded out. Most of the time in west Texas, AZ & Southern CA. Truck is deleted, tuned and puts out north of 450hp. FASS fuel system w/ filters & separator changed every 10K. I also swapped over to a 180* thermostat as the truck just ran wayy to hot w/ the OEM t-stat. Oil filter is a Donaldson DBL7349 and it too is replaced at every OCI. I really enjoy this truck and like it much more than my 5.9L Cummins / Dodge, its a shame Nissan discontinued them. I have a buddy that works for HPL & set me some to try, so this current fill is of their HPL 15w40. I will sample it as well & we will see how we are tracking after 3 OCI's w/ the HPL 15w40. All that being said the UOA for the Rotella T6 15w40 is pretty outstanding so it will be interesting to see how the HPL compares.