Ford Ranger Maintaince And Repair Manual page 142

If necessary, add the proper grade of lubricant until fluid trickles out
4. Remove the fill plug and make sure that the gear oil is up to the bottom of the fill hole. If a slight
amount of lubricant does not drip out of the hole when the plug is removed, additional lubricant
should be added. Use hypoid gear lubricant SAE 80 or 90.
If the differential is a Traction−Lok limited−slip unit, be sure to use 4 oz. of Ford Friction Modifier
C8AZ−19B546−A or equivalent special limited−slip additive with the lubricant.
5. Once you are finished, install the fill plug, then (if raised) remove the jackstands and lower the
vehicle.
DRAIN & REFILL
Drain and refill the drive axle housings every 100,000 miles (160,000 km) or any time the vehicle is driven in
high water (up to the axle). Although some fluid can be removed using a suction gun, the best method is to
remove the axle housing cover (if equipped) to ensure that all of any present contaminants are removed. As
with any fluid change, the oil should be at normal operating temperature to assure the best flow and removal
of fluid/contaminants.
Most front and some rear drive axle assemblies do not have a removable cover for fluid draining.
However, these units may have a drain plug instead. Drain plug equipped drive axles can be serviced in
the same manner as the manual transmission and/or transfer case. If no drain plug is found, you will
need to use a suction gun through the fill hole to remove the fluid. The procedure below is for housing
cover equipped axles.
1. Drive the vehicle until the lubricant reaches normal operating temperature.
2. If necessary for access, raise and support the vehicle safely using jackstands, but be sure that the
vehicle is level so you can properly refill the axle when you are finished.
If a suction gun is used to drain the fluid, remove the fill plug and insert the suction tube into the fill
hole until it rests at the lowest most point inside the housing. Operate the suction gun as per the
manufacturers directions. When the fluid is completely removed, skip to the differential filling
procedure.
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HOW TO USE THIS BOOK
DRAIN & REFILL