I am preparing to change the differential gear oil in my 2001 motor home, with 97k miles. I got no service records when I bought the motor home in Dec. 2021, so I'm anxious to get fresh fluid in the diff.
The service manual for the rear diff (Meritor) includes 5 different GL-5 multi grade viscosities, ranging from 75W-90 to 85W-140. Beyond which viscosity to use in expected outdoor temperatures, the manual makes no recommendation of one of these grades over another. Any of the listed grades will work within the climate that I plan on driving the motor home in, so no issues there.
I like the idea of running an 80W-90 in hopes that it will help a little with fuel economy. But would and XXW-90 offer enough protection for the diff in a rig with a 32,000 GVWR? If a XXW-90 isn't enough to protect the diff, then why would Meritor include them in the service manual? So then I question if I should be selecting one of the XXW-140 gear oils, to give more protection.
Any advice from those of you out there with experience operating and maintaining heavy equipment?
The service manual for the rear diff (Meritor) includes 5 different GL-5 multi grade viscosities, ranging from 75W-90 to 85W-140. Beyond which viscosity to use in expected outdoor temperatures, the manual makes no recommendation of one of these grades over another. Any of the listed grades will work within the climate that I plan on driving the motor home in, so no issues there.
I like the idea of running an 80W-90 in hopes that it will help a little with fuel economy. But would and XXW-90 offer enough protection for the diff in a rig with a 32,000 GVWR? If a XXW-90 isn't enough to protect the diff, then why would Meritor include them in the service manual? So then I question if I should be selecting one of the XXW-140 gear oils, to give more protection.
Any advice from those of you out there with experience operating and maintaining heavy equipment?