We usually don’t think about our rear differentials…until there is a problem. We should go ahead and change the fluid. We change our engine oil …but don’t think about the drive shaft. If we don’t take care of the differential it will be rather expensive (time consuming and very special tools to repair). So the easy and effective way to prevent this is to change the fluid. Simple and easy! Here is a 1999 Ford F150 that we changed. Please note that the quality of the fluid makes a good investment. That is why I personally use AMSOIL products. If you need any AMSOIL products or have any questions give us a call anytime Power Synthetics 501-545-9339
Step 1 : Secure the vehicle on jack stands or ramps. Locate the differential drain bolt or remove the differential cover as shown on this Ford F150 1999. Loosen and remove.
Step 2 : Allow time for the gear oil to completely drain. Take a look at the differential and clean it if necessary. If it has never been cleaned, you may need to clean it up. Also make sure you clean the magnet that holds metal shavings. Replace the drain bolt. Wipe any excess gear oil from the case.
Step 3 : Some cars have premade gaskets. If not, use a liquid gasket product designed for harsh conditions and oil exposure, such as Permatex Ultra Black. Lay a single bead on the mating face of the cover and draw a circle around each mounting hole, then bolt the cover in place with just enough clamping force to flatten the bead. Let it harden according to the instructions, then tighten the bolts to your vehicle’s specs with a torque wrench.
Step 4 : Use the highest-quality gear oil you can afford to fill the differential such as AMSOIL Severe Gear. The weight and capacity will be listed in your owner’s manual; your differential will usually hold as much as 3 quarts. Be sure to read that manual, though, because some limited-slip differentials require a secondary friction-modifying additive such as AMSOIL Slip Lock. Fill the differential directly from the bottle if you’ve got clearance, but if space is tight, you can get a pump or extension hose to make the job easier. The bottom of the plug hole is the maximum fill line, so when oil starts dripping out, you’re finished. Install the plug, torque it to spec, and you’re good for tens of thousands of miles.