What suitable fillter for mobil gear oil 634? typically I use gear oil 85W140 and replace with gear oil 634 then got pressure drob too much in the fillter.

Thanks.
Phoo:

Phoo,

You may be experiencing some differences in viscosity upon changing from 85W140 to Mobil 634. The 634 oil is a 460 Iso Grade lubricant, meaning that it has a nominal viscosity of 460 centistokes at 40 deg C. Not sure which 85W140 oil you are using, but the 85W140 designation can apply to oils with a viscosity at 40 deg C from 320 to 460. A search of a few examples online shows some products with a viscosity closer to 330 centistokes at 40 deg C. If you previously used the same filtration setup with your 85W140 that has a lower viscosity, and are now pumping a more viscous 634 at the same temperature, you will expect to experience higher differential pressure across the filter elements. When selecting a replacement lubricant, a number of factors must be considered, including the operating viscosity at operating temperature. This viscosity must be within the design requirements for the bearings and gears that are lubricated in the system. Also, the flow curves for both the filtration and oil pump must be checked to ensure that the new oil viscosity will allow the system to operate within design specs. If the gears, bearings and pump are adequately served by the new 634 oil, then you can consider changing the filter media or perhaps the filter housing and media, to a combination where the flow curve is optimized, or at least operational, with the selected viscosity.

Rich Wurzbach
CLS, OMA-I, LLA-I
MRG Power Labs

Good Call Rich.

How you doing these days?

Mike