Why the thicker oil?
I go by mileage even thought the DIC calculates by RPMs and for the newer trucks, time.
Truck went 3,353 miles in 97 hours for first oil change.
Truck went 6,923 miles in 214 hours for the next one.
Then she went 5,051 miles in 185 hours and OLM said 33%.
The following went 5,185 miles in 193 hours and OLM said 44%.
Next one went 4,140 miles in 137 hours.
Last one went 6,216 miles in 217 hours and OLM still said 37%.
As mentioned previously, I was getting concerned that Mobil 1 was now a little too thin for my truck and switched to ACDelco's new oil for aluminum block motors. It is very similar numbers wise to the new Rotella Gas Truck by Shell. The motor uses no oil.