These drivetrain components utilize gears, bearings, and in the transfer case and transmission, also use shift forks and synchro parts (to make shifting easy).
They all use fluids: some standard gear oil and others, specially formulated synthetic oils. Though not subject to the heat generated within an automatic transmission, standard transmissions and differentials still require regular fluid services.
Intense friction is generated between the gears, bearings and other parts. The lubricating oil is not filtered, leaving metal particles free to cause wear as the fluid circulates through the bearings and gears. Water contamination of the fluid is another issue of concern, especially on 4WD differentials.
During our service of these components we drain the fluid and refill it with the correct fluid type. In the case of differentials with removable covers we always remove the cover to drain the fluid, clean the cover and inside of the differential and reinstall the cover.
Recommended Frequency: Every 48,000KM or 30 months (whichever comes first); service will be recommended sooner if fluid is contaminated or discoloured.