I have a motorhome on a 1987 P30 chassis with 57,000 original miles. Engine has been well maintained and the oil was always changed once a year or 3000 whatever came first it's entire life.
I would like to run a 15w40 heavy duty oil due to the higher viscosity and higher zinc due to the flat tappet cam, but seems like the diesel oils are losing their "s" rating and only having a "c" rating now.
I typically run at 3000 RPM and travel more in extreme hot. May go up to the snow/mountains once a year but wouldnt be up there much colder than 20 degrees Fahrenheit.
I also run Lucas and would run a zinc additive if I couldn't find a heavy duty oil.
I have included the page from the GM dealer service manual for the chassis that shows straight 30 is the recommended.
Looking for recommendations on the best route to go since I can't seem to find a 15w40 heavy duty "s" oil anymore.
Thanks
I would like to run a 15w40 heavy duty oil due to the higher viscosity and higher zinc due to the flat tappet cam, but seems like the diesel oils are losing their "s" rating and only having a "c" rating now.
I typically run at 3000 RPM and travel more in extreme hot. May go up to the snow/mountains once a year but wouldnt be up there much colder than 20 degrees Fahrenheit.
I also run Lucas and would run a zinc additive if I couldn't find a heavy duty oil.
I have included the page from the GM dealer service manual for the chassis that shows straight 30 is the recommended.
Looking for recommendations on the best route to go since I can't seem to find a 15w40 heavy duty "s" oil anymore.
Thanks