How to Change the Differential Fluid on Vehicles

by Contributing Writer; Updated June 12, 2017

Vehicles are hard-working, reliable Vehicles that can take as much punishment as their owners dish out Vehicles them. Part of the drive line on these Vehicles that often goes through the roughest and most intense punishment is the differential. The differential is the part of the transmission drive that contains the gears that spin the axle shafts. While the workings of the differential are fairly intricate, there are a few maintenance routines that, if performed regularly, will assure a long and useful life Vehicles your Vehicles. One such job is replacing the differential fluid. Changing the differential fluid is not difficult and can be performed in a single afternoon.

Under The Hood:

 How to Change the Differential Fluid on a GMC Truck

Park the truck somewhere level and jack the front of the vehicle up.

Crawl under the rear of the truck and locate the differential, which looks like a round case connected to the truck's driveshaft. On the bottom-center of the transfer case is the drain plug; remove it with a socket wrench.

Place the waste pan under the drain hole and allow the fluid to drain into it. Replace the drain plug and remove the bolt for the fill hole on the right side of the differential case using a socket wrench.

Insert the plastic tube from the fluid pump into the hole and pump the fluid into the transfer case until it is full. Replace the filler hole bolt and lower the truck off of the jack.

Items you will need

  • Waste pan

  • Manufacturer-recommended differential fluid

  • Socket wrenches

  • Fluid pump

  • Car jack

 How to Change the Differential Fluid in an Infiniti G35

Jack up the car and place two jack stands under the front and two at the back, or drive it onto automobile ramps and securely set the parking brake. Place a drip pan underneath the differential housing near the rear of the car.

Loosen the fill plug bolt on the passenger side of the differential housing using a 10 mm hex socket and an extension, if necessary. Remove the plug and pry the washer from the plug using a flat-head screwdriver. Discard the washer. Wipe the plug well with a clean rag or towel to remove fluid and any fine metal shavings. Set a new washer in place and set aside the plug.

Locate and remove the drain plug at the center rear of the differential housing. Allow the fluid to drain into the drip pan. Remove and discard the washer and clean the plug with a rag or towel. Slide a new washer on the plug. Replace the drain plug and torque it down to 24 to 26 foot-pounds.

Fill a fluid pump with oil and insert the hose end into the fill hole. Pump the fluid into the differential, refilling the pump as needed. Stop the filling process when the fluid begins to overflow the hole. Wipe excess oil off the housing and replace the fill plug; torque it to about 26 foot-pounds.

Items you will need

  • Automobile jack

  • 4 jack stands or 2 automobile ramps

  • Drip pan

  • Socket wrench and extension

  • 10 mm hex socket

  • Flat-head screwdriver

  • Clean shop rags

  • 2 differential plug gaskets/washers

  • Fluid pump

  • 2 quarts 75W-90 or 80W-90 gear oil

 How to Change the Differential Fluid in a Ford Explorer

1999 Ford Explorer and Earlier Models

Park the Explorer on a level paved surface. Place wheel chocks in front of the front wheels. Raise the rear of the Explorer with a jack and support it with a jack stand placed under each axle tube.

Place a drain pan under the center of the axle housing where the differential cover attaches to the housing.

Use a ratchet and socket to loosen all of the bolts on the cover. Remove all of the bolts except for the top three. Loosen the top three bolts until they are almost all the way out. This prevents a big splash when you break loose the cover. Use a flat-head screwdriver to carefully pry the cover loose -- just enough to break the seal. Catch the gear oil in the drain pan. Remove the rest of the bolts and remove the cover.

Remove the old cover gasket from the cover and axle housing. Use a putty knife to carefully scrape away any remaining gasket material from the cover and housing.

Spray the cover with parts cleaner and wipe it clean with a shop rag. Wipe out the inside bottom of the axle housing to remove any remaining gear oil and sludge. Spray a shop rag with parts cleaner and clean the gasket mating surface on the axle housing.

Run a bead of black RTV silicone sealant – about 1/4 inch wide – around the center of the cover. Run a bead around each bolt hole. Let the sealant set for a few minutes or as indicated on its instructions. Mount the cover on the axle housing. Install and tighten the bolts.

Use a wrench to remove the fill plug on the cover. Fill the axle with 75W-140 gear oil until the gear oil reaches the bottom of the filler hole. If you have a limited slip differential, add 4 ounces of limited slip additive before filling with gear oil. Install and tighten the filler plug.

2000 Ford Explorer

Park the Explorer on a level paved surface. Place wheel chocks in front of the front wheels. Raise the rear of the Explorer with a jack and support it with jack stands on the frame.

Place a drain pan under the center of the rear axle. Use a ratchet to remove the drain plug from the rear cover. The ratchet head fits into the square hole in the center of the plug. Allow the gear oil to drain into the pan. Install and tighten the plug.

Use a ratchet to remove the filler plug. It is above and to the right of the drain plug. Fill the axle with 75W-140 synthetic gear oil. Use limited slip additive if needed. Install and tighten the filler plug.

Items you will need

  • Wheel chocks

  • Jack

  • Jack stands

  • Drain pan

  • Ratchet and socket set

  • Flat-head screwdriver

  • Putty knife

  • Parts cleaner

  • Shop rags

  • Non-hardening gasket sealer

  • New differential cover gasket

  • Limited slip friction additive (optional)

  • 3 quarts 75W-140 gear oil (synthetic gear oil for 2000 and later)

About the Author

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