I'm looking for a suggestion for the oil to use in a NP203 transfer case.
The owner's manual recommendation is to use SAE 30 non-detergent motor oil. Is there something that would be better from the perspective of protecting gears than a motor oil?
For those not familiar with the NP 203: It is an all wheel drive transfer case for full size pickup trucks. The transfer case has a two speed gearbox at the front much like a non-synchro manual transmission rather than the planetary set found in most transfer cases. It has a differential behind the range box and a chain to the front output.
The lubrication for the range box is just like a manual transmission. The lay-shaft sits about 1/2 submerged and carried oil lubricates the main shaft bearings and gears.
The differential is lubricated by oil carried by the chain using an oil catch. The rear output bearings are then lubricated by splash captured off the differential.
I've read warnings on the internet to not use gear oil because the rear output bearings don't get oil from the multiple relay of oil up from the sump. So it would seem that a lighter oil would be necessary. But I question the long term life when lubricated with a motor oil vs. an oil package designed for gears, roller bearings and ball bearings.
The owner's manual recommendation is to use SAE 30 non-detergent motor oil. Is there something that would be better from the perspective of protecting gears than a motor oil?
For those not familiar with the NP 203: It is an all wheel drive transfer case for full size pickup trucks. The transfer case has a two speed gearbox at the front much like a non-synchro manual transmission rather than the planetary set found in most transfer cases. It has a differential behind the range box and a chain to the front output.
The lubrication for the range box is just like a manual transmission. The lay-shaft sits about 1/2 submerged and carried oil lubricates the main shaft bearings and gears.
The differential is lubricated by oil carried by the chain using an oil catch. The rear output bearings are then lubricated by splash captured off the differential.
I've read warnings on the internet to not use gear oil because the rear output bearings don't get oil from the multiple relay of oil up from the sump. So it would seem that a lighter oil would be necessary. But I question the long term life when lubricated with a motor oil vs. an oil package designed for gears, roller bearings and ball bearings.