My work truck is a 2008 Dodge Ram 4.7 6spd with 85k miles. Truck sees 3-4k miles per month with alot of offroad driving in dusty conditions, lots of idling, high speed driving, heavy loads, and frequent trips to redline. Ambient temps get up to & above 100 deg in the summer, which is when the truck gets worked hardest. Manufacturer calls for a 5w20, even though 5w30 was specced before CAFE became such a priority.
Previously run oils:
M1 0w20 - run from 1st OC up to about 35k miles. Seemed to work fairly well at 7500 mile OCI's, but valvetrain was always a bit loud with this oil and I never felt comfortable running it past 7500 miles due to low TBN
PP 5w20 - only run for one oil change as if caused a noisy valvetrain that got VERY loud after the first 5k miles...changed out at 6k
German Castrol 0w30 - run from 45k-80k (with a couple changes of M1 0w40 in between) at 7500 OCI. The GC made the engine run a bit smoother and considerably quieter, but fuel economy dropped off a couple tenths. Tried to run the GC up to 10k, but engine started complaining at about 9k. Similar results with the Mobil 1 0w40.
Recently switched back to the M1 0w20 because WM had it on clearance for $4/qt, and I've definitely regained a bit of power & mpg.
Are there any 20wt synthetic oils out there that can comfortably handle 10k OCI's under such severe conditions? Or would I be better off going back to a higher-HT/HS oil with more TBN reserves?
Previously run oils:
M1 0w20 - run from 1st OC up to about 35k miles. Seemed to work fairly well at 7500 mile OCI's, but valvetrain was always a bit loud with this oil and I never felt comfortable running it past 7500 miles due to low TBN
PP 5w20 - only run for one oil change as if caused a noisy valvetrain that got VERY loud after the first 5k miles...changed out at 6k
German Castrol 0w30 - run from 45k-80k (with a couple changes of M1 0w40 in between) at 7500 OCI. The GC made the engine run a bit smoother and considerably quieter, but fuel economy dropped off a couple tenths. Tried to run the GC up to 10k, but engine started complaining at about 9k. Similar results with the Mobil 1 0w40.
Recently switched back to the M1 0w20 because WM had it on clearance for $4/qt, and I've definitely regained a bit of power & mpg.
Are there any 20wt synthetic oils out there that can comfortably handle 10k OCI's under such severe conditions? Or would I be better off going back to a higher-HT/HS oil with more TBN reserves?