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How do I Change Differential Oil in Vehicles

by Contributing Writer; Updated June 12, 2017

The differential on a Vehicles pickup takes power generated by the engine and channeled through the transmission and directs it to the rear wheels. The differential must be adequately lubricated to prevent the internal moving parts from wearing down. Occasionally the gear oil must be replaced to replenish it's ability to lubricate. Changing the differential oil on a Vehicles can easily be accomplished by the Vehicles owner, with only a few simple tools and about an hour to work.

Under The Hood:

 How do I Change Differential Oil in a 1994 Isuzu Trooper?

Park your Isuzu on a level ground and raise the front and rear with a floor jack. Support it with two jack stands under the front frame and two jack stands under the rear frame.

Remove dirt from around the filler plug located on one side of the differential and the drain plug underneath with a wire brush to prevent contamination of internal components. Try to loosen both plugs with a ratchet and socket. This way you will make sure the plugs are not rusted and frozen in place. If you are unable to loosen the plugs, soak them with penetrating oil for several hours before changing the oil. On Trooper models with mounting bolts on the side cover of the differential instead of a drain plug, try to loosen the mounting bolts as well. Otherwise, soak the bolts with penetrating oil for a few hours.

Place a 3-quart drain pan under the differential and remove the drain plug at the bottom of the differential. Remove the filler plug with a ratchet and socket or gradually loosen the side-cover mounting bolts with the ratchet and socket until you remove all the bolts. Carefully pry the cover off with a screwdriver and remove the old gasket. Let the oil drain completely.

Remove dirt, oil and grease form the case cover and housing with a brush, shop rag and solvent, if your Trooper comes equipped with it. Apply a coat of gasket sealant to the housing and cover mating surfaces. Place a new gasket on the cover and replace the cover on the housing. Install the mounting bolts finger tight and then tighten the bolts to 30 foot-pounds with a torque wrench.

Replace the drain plug with the ratchet and socket.

Fill the front differential case with 3.2 pints and the rear differential case with 3.9 pints of standard GL-5 hypoid type gear oil. Use a viscosity of SAE 75W-90 in the front axle for all temperatures. For normal temperatures at 50 degrees F, use SAE 140W. For temperatures below 50 F, use SAE 80W/90. For temperatures between 0 and 90 F (-18 to 32 C), use SAE 80W/90. Pour the oil through the filler hole with a hand pump. Check with your index finger that the oil is at the lower edge of the filler hole.

Replace the filler plug with the ratchet and socket.

Check for leaks around the drain plug or cover and lower your Trooper with the floor jack.

Items you will need

  • Floor jack

  • 2 jack stands

  • Wire brush

  • Ratchet

  • Socket

  • Penetrating oil (optional)

  • 3-quart drain pan

  • Standard screwdriver (optional)

  • Shop rag

  • Solvent (optional)

  • Gasket sealant (optional)

  • New differential cover gasket (optional)

  • Torque wrench (optional)

  • 7.1 pints of GL-5 hypoid gear oil

 How to Change Differential Oil in an F250

If you've driven recently, give the fluid within the differential at least an hour to cool down.

Place a large fluid drain pan below the differential.

Remove all but the top differential cover bolts with a wrench. The differential cover is located on the back of the differential, meaning the side of the differential which faces the back of the truck.

Pry the bottom of the differential cover away from the differential with a screwdriver until the differential fluid begins to drain into the fluid drain pan.

Remove the top bolts from the differential cover with a wrench, then pull the cover off of the differential.

Pull the differential cover gasket off of the cover, then wipe down the gasket’s mating surfaces on the differential cover and on the differential with a lint-free rag. These surfaces must be as clean as possible to ensure that the new gasket seats properly.

Apply a single bead of silicone gasket sealer to both of the cover’s mating surfaces, then press a new cover gasket onto the cover.

Position the differential cover onto the differential, then install and tighten each of the cover’s retaining bolts with a wrench.

Remove the differential’s fluid filler bolt from the driver’s side of the front of the differential with a wrench.

Insert a funnel into the filler hole, then pour differential fluid into the differential through the funnel just until fluid begins to run out of the filler hole.

Remove the funnel, then tighten the fluid filler bolt into the differential with a wrench.

Items you will need

  • Large fluid-drain pan

  • Wrench

  • Screwdriver

  • Lint-free rag

  • Silicone gasket sealer

  • Funnel

 How to Change the Differential Oil on a Dodge Ram

Draining the Differential Oil

Raise the rear of the vehicle using an automotive jack, and support with jack stands placed under the rear axle.

Locate the differential cover on the back side of the rear axle. Place a waste oil collection pan underneath the cover.

Unscrew the fill plug on the cover using a wrench.

Beginning at the bottom of the cover, loosen but do not remove the bolts that secure the differential cover to the axle housing using a socket.

Unscrew the bolts on the bottom of the cover, using a socket. At this point oil might begin to seep from the bottom of the differential cover.

Tap the side of the cover with a rubber mallet if oil does not begin to seep from the bottom of the cover. Allow the differential to drain completely.

Unscrew the remaining bolts that secure the cover to the axle housing using a socket.

Remove the cover from the axle housing.

Refilling the Differential Oil

Clean the differential cover using an automotive solvent. Be sure to remove the gasket sealant off the mating surface using a flat razor blade. Allow the cover to air dry.

Clean the gasket sealant off the mating flange on the axle housing using a flat razor blade and an automotive solvent. Allow the surface to air dry.

Run a bead of RTV (room temperature vulcanizing) silicone sealant on the axle-housing mating surface. Be sure to run the bead inside the bolt holes.

Lift the differential cover into position on the rear axle.

Screw in the bolts that secure the cover to the rear axle housing and tighten using a socket.

Fill the differential with fresh gear oil, using a gear oil pump. Fill the differential to the bottom edge of the filler plug hole in the differential cover.

Screw the filler plug into the differential cover using a wrench.

Lower the vehicle.

Items you will need

  • Automotive jack

  • Jack stands

  • Wrench set

  • Socket set

  • Rubber mallet

  • Flat razor blade

  • Automotive solvent

  • RTV silicone sealant

  • Gear oil

  • Gear oil pump

About the Author

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