Rear differential fluid on Ford F-150 lubricates the rear axle gears and internal parts and also acts as a coolant for those parts in heavy towing applications.

How to Change Rear Differential Fluid on Ford F150? To replace the rear differential fluid on Ford F-150, remove the differential cover to drain the worn-out fluid. Then, clean its interior for any debris or accumulated gunk. Next, reinstall the cover using silicone sealant with a new gasket to prevent leakage. Finally, refill the fluid removing the filler plug up to maximum capacity.

Ford recommends it to replace after regular intervals to slow down the wear and tear of differential parts.

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How to Change Rear Differential Fluid on Ford F150?

This article guides Ford F-150 owners to change the rear differential fluid on their pickup trucks by themselves.

Park the truck on a level surface, apply the jack under the rear axle, and chock the front wheels to restrict its movement.

Wait for half an hour after turning off the engine to cool down the differential fluid.

Use protective gear like a goggle, helmet, and gloves.

Remove the differential cover

First of all, remove the brake lines of the auto-braking system from the rear differential by pulling its pins away.

Mark their positions so that you can reinstall them accurately in their place.

After that, using an impact wrench or ½-inch ratchet spanner, remove the numerous bolts that secure the differential cover in its place.

Don’t detach all of them in a sequence but loosen them in a zigzag manner to prevent skewing its surface.

Keep 1-2 bolts on top of the differential body in a loosely open position to avoid falling off the cover when you drain the old fluid.

Drain the expired fluid

Place a large drain pan underneath the differential housing. Next, insert a putty knife or flat head screwdriver between the cover and its housing.

Next, use a wooden or rubber hammer to push it between the two on the bottom of its body from side to side.

Keep on doing so until all fluid in the housing drains in the pan.

However, avoid pushing the knife or screwdriver too deep in the housing to prevent damage to the internal gears.

After removing the cover, drain the remaining fluid in the sump of housing using your hand or clean cloth.

Clean the differential cover

Remove the differential cover, and you will find its surface covered with debris and metallic sludge.

Wipe it with a clean cloth to remove all the blackish material and fluid on its inner side. You can also use any cleaning agent for efficient removal of all the gunk.

Use a scouring pad to clean the mating surfaces of old sealant pieces and make them plain for maximum bonding to prevent any leakage.

Remove the silicone sealant

After cleaning the differential cover and its mating surface, the next step is to remove the silicone sealant on the mating surface of the rear differential housing.

First of all, as a preventive measure, cover the internal parts and gears with towels or rags to prevent any gunk or debris from entering between them.

Next, use a spray cleaner and a plastic knife to scrape the sealant pieces on the surface.

In the end, use a scouring pad to remove the remaining material on the mating surface and make it plain.

Clean the rear axle

Clean the axle with the brake cleaner to remove any debris on its surface and gears.

The bottom fluid reservoir contains a sump to collect the rubble and prevent it from mixing with the rear axle parts.

Drain it and clean it with a paper towel as a part of the service.

Apply the silicone sealant and install the gasket

Apply a thin line of the silicone sealant or gasket maker on the mating surface of the differential cover.

Next, install the new gasket above the silicone layer and gently press it for uniform bonding between the both.

Wait for 15-20 minutes to dry the sealant. Remember to align the bolt holes of the cover with the gasket for their easy installation.

Next, apply a thin layer of silicone sealant on the gasket surface of the differential. Finally, firmly press its cover against its housing to prevent any leakage in the future.

Loosely fix 3-4 screws to hold it in its place. Tighten the nuts in order from bottom to top and then sides and corners.

Torque them gradually to prevent flushing the cover and leakage of the fluid. Next, apply the final torque of 30-35 lb-ft on all bolts recommended by the manufacturer.

Reinstall the ABS plugs in their place as per initial marking for their correct operation. Wait for 15-20 minutes before starting the refilling process to allow the silicone to dry up completely.

Remove the filler plug and clean it

Locate the filler plug to remove it using an appropriately sized socket wrench. Remove its cover and clean its interior magnet to remove any debris and metallic particles. I recommend using a clean cloth with brake cleaner for efficient cleaning.

Refill the rear differential fluid

Insert a small funnel or, using a hand pump, pour the recommended grade rear differential fluid through the filler hole. Keep on pushing the oil until it starts to come out of the hole.

After refilling the fluid, clean its surface and filler plug for any spilled oil.

Then, reinstall or replace the plug nut and tightly secure it in its place.

Quantity and type of rear differential fluid

Its quantity depends on the shaft size and type. It takes about 2-3 quarts from 8.8″ to 10.25″ axle sizes.

Ford recommends using synthetic rear axle fluid having a weight rating of SAE 75W-140 of any renowned brand.

However, you should check the owner manual of the specific model year of your truck and use the mentioned rating oil for your vehicle.

In the case of a limited-slip differential system, you also need to add a friction modifier to prevent clutch operation malfunction.

How often should you replace the rear differential fluid on Ford F150?

Ford recommends changing the rear differential fluid from 100,000 to 350,000 miles depending upon the truck’s model year, age, and condition.

It also depends on the extent of the operation and its intended purpose.

Experts recommend changing the differential fluid after 25,000-35,000 miles to use it for heavy towing applications.

While for light usage, replace the rear differential fluid after 60,000-65,000 miles for the truck’s safety and longevity of its service life.

Moreover, this oil also acts as a coolant in heavy towing applications; therefore, its cleaning and replacement are essential for the enhanced life of the axle and rotating gears.