How to Change Gear Oil in Vehicles

by Contributing Writer; Updated June 12, 2017

They say that races are won by the amount of preparation you put into your bike before you even hit the track. Preparing your motorcycle beforehand can spell the difference in seeing the checkered flag or a dreaded DNF. A critical step in the preparation process is changing your Vehicles transmission -- or gear -- oil, which helps to protects the transmission and clutch from the stresses of competitive motocross riding. This is such an important procedure that Vehicles recommends changing the transmission oil every three races to reduce the possibility of a transmission failure while on the track.

Under The Hood:

 How to Change Gear Oil in a Dodge RAM 1500

Place the oil bucket beneath the front or rear differential.

Loosen the retaining bolts for the differential cover until you have a substantial gap between the bolt head and the cover. Crack the seal and allow the fluid to drain into the oil bucket.

Remove the cover entirely and spray the parts with a brake parts spray cleaner. Allow the cleaner to drain off into the bucket.

Replace the gasket. You may have to scrape off old gasket material with a scraper or screwdriver. Install the gasket, replace the cover. Hand-tighten all bolts and use the socket wrench to fully tighten them. Torque the bolts to 20 foot pounds of torque.

Remove the fill plug using a hex-head ratchet if a metal fill plug is present. Remove the rubber fill plug if equipped using a screwdriver. Fill the differential with SAE 75w90 gear oil until the oil level is flush with the bottom of the fill plug hole. A little line of fluid will run out when the gearbox is full. Replace the rubber or metal plug.

Items you will need

  • 10 pints of SAE 75w90 gear oil

  • Ratchet

  • Hex head ratchet

  • Oil bucket

  • Rag

  • Brake parts cleaner

  • Replacement gasket

  • Scraper or screwdriver

 How to Change Gear Oil in a Chevy 10 Bolt

Replace Gear Oil in 10-Bolt Chevy Differential

Park the car on a flat, level surface and set the parking brake.

Jack the rear-end of the car up using the floor jack until the rear axle is high enough to clear the automotive jack stands. Place the rear axle on jack stands spaced approximately thirty-two inches on either side of the differential.

Place the drain pan beneath the 10 bolt differential to catch the gear oil as it is drained.

Remove the drain plug from the bottom of the differential cover using the 1/2-inch combination wrench. Slowly unscrew plug until gear oil starts to drain around plug into the drain pan.

Remove the 10 bolts securing the differential cover to the rear-end using the 9/16-inch combination wrench. Slowly remove the bolts while allowing residual gear oil to drain into drain pan.

Remove the differential cover from the rear-end and set aside. Scrape off the cork gasket from the 10-bolt housing with a putty knife.

Install new cork gasket onto 10-bolt housing and replace differential cover. Hold cover in place and install the ten bolts into the cover hand tight. Complete installation of bolts by tightening completely with 9/16-inch combination wrench.

Install drain plug into differential cover using 1/2-inch combination wrench.

Remove the top fill plug from the differential housing using the 1/2-inch combination wrench.

Place small funnel into fill hole now accessible with fill plug removed. Fill rear housing to within 1/2-inch of fill hole.

Replace fill plug using 1/2-inch combination wrench and wipe any excess oil from differential.

Lower the car from the automotive jack stands using the floor jack. Release the emergency brake.

Items you will need

  • Car jack

  • One gallon drain pan

  • 9/16 inch combination wrench

  • 1/2 inch combination wrench

  • Shop rags

  • 3 quarts 75w differential gear oil

  • 2 automotive jack stands

  • Putty knife

 How to Change Gear Oil in a CR250

Start your CR250R and left it idle for two or three minutes to warm the transmission oil. Stop the engine and place the CR250R on a stand to hold it in a level position. Let the oil settle and cool slightly for another minute.

Unscrew the oil filler cap from the top of the clutch cover on the right side of the engine, just in front of the kick-start lever. Place an oil drain pan below the engine.

Remove the drain bolt from the bottom of the engine, using a 16 mm socket and a ratchet. Remove and discard the crush washer from the drain bolt, and wipe the drain bolt threads with a rag. Let the transmission oil drain from the engine until the flow of oil reduces to a light drip.

Wipe the area surrounding the oil drain hole clean, Place a new crush washer on the drain bolt, then thread it into the engine by hand. Tighten the bolt to 18 foot-pounds, using a torque wrench.

Remove the oil level check bolt -- the only bolt with a Phillips-type head on the clutch cover -- using a Phillips screwdriver. Fill the transmission with Honda GN-4 SAE 10W-40 engine oil until a small amount of oil drains from the check bolt hole while the bike is level. Wipe the check hole clean and screw the check bolt into place. Tighten the bolt to 7 foot-pounds and screw the oil filler cap into place by hand.

Items you will need

  • Dirtbike stand

  • Drain pan

  • 16 mm socket

  • Ratchet

  • Rags

  • Crush washer (Honda part no. 94109-12000)

  • Torque wrench

  • Phillips screwdriver

  • 1 quart of Honda GN4 SAE 10W-40 engine oil

 How to Change the Gear Oil on a 2003 Ford F-150 Rear End

Raise the rear of the F-150 using a jack. Place jack stands beneath the rear axle housing, just inside both rear wheels. The farther you place the jack stands apart, the more stability you will have for this project. Lower the truck onto the jack stands.

Lie beneath the rear bumper of the truck and slide yourself into position to access the rear differential. Visually inspect and locate the rear-differential fill plug. If the plug is not on the rear of the differential, the plug will be on the upper driver's side of the differential, facing the front of the car. Remove the plug with a 1/2-inch drive ratchet placed directly onto the head of the plug.

Place a drain pan or empty 1-gallon container beneath the differential. Insert the vacuum end of a pump siphon into the differential fill hole and slide the tube to the bottom of the differential. Place the other end of the pump siphon into the drain pan, or an empty 1-gallon bottle.

Pump the siphon repeatedly until you have completely emptied the rear differential. The siphon hose will make a gurgling sound, when the differential is empty.

Add 4 oz. of friction modifier to the gear oil, if the gear oil does not have the modifier already included. Add 1 3/4 qts. of 75-140w full-synthetic gear oil to the rear differential if you have an 8.8-inch rear-end identified by 10-bolts on rear cover. Add 2 1/2 qts. of 75-140w full-synthetic gear oil if you have a 9.75-inch rear end identified by 12-bolts on the rear cover.

Replace the gear-oil fill plug, and tighten the plug snug with a 1/2-inch ratchet. Do not over tighten the fill plug, as there is no stopper on the plug. Turn the plug a quarter turn beyond the snug point to ensure the plug seals the rear differential.

Lift the rear of the truck off of the jack stands, and then remove the stands from beneath the truck. Lower the truck to the ground.

Items you will need

  • 1 ton or greater capacity jack

  • 2 jack stands

  • 1/2-inch drive ratchet

  • Hand pump or electric pump siphon

  • 1-gallon drain pan, or empty 1-gallon jug

  • 75-140w full synthetic gear oil (1.75-quarts for 10 bolt rear, 2.5-quarts for 12 bolt rear)

  • 4 ounces friction modifier (If not included in the gear oil)

 How to Change the Gear Oil in a Roketa 250CC Go Kart

Remove the Allen-head drain bolt on the top of the gear box, located next to the gear box breather hose, using an Allen wrench.

Insert the hose of a transfer pump into the gear box through the bolt hole. Place the pump's output hose into a two-quart resealable plastic bottle. Suck out the old gear oil using the transfer pump.

Pull the hose out of the gear box, then hand-thread the drain bolt into the gear box. Tighten the gear box to 7.6 foot-pounds using a torque wrench.

Pull the breather tube off the oil fill bolt at the top of the gear box. Unscrew the oil fill bolt using a box-end wrench. Fill the gear box with SAE 80W-90 GL-4 gear oil until the oil level is 1 inch below the filler hole, using a hand-operated oil gun.

Wipe away any spilled gear oil from the gear box, then hand-thread the oil fill bolt into place. Tighten the oil fill bolt to 18 foot-pounds. Push the breather hose onto the filler bolt.

Items you will need

  • Allen wrench set

  • Transfer pump

  • Resealable plastic bottle, 2-quart

  • Shop towels

  • Torque wrench

  • Box-end wrench

  • SAE 80W-90 GL-4 gear oil

  • Oil gun

 How to Change the Gear Oil on a Dodge Dakota

Park the Dakota and engage the emergency brake.

Slide an oil bucket beneath the differential. The process is the same for both front and rear differentials.

Loosen the bolts surrounding the differential cover with a socket wrench. Remove the bolts and set them to the side. Remove the cover. You might have to insert a flat-head screwdriver between the cover and the differential to pry it loose.

Scrape off all the gasket material from the cover and the differential with a scraper. Inspect the gears inside the differential for damage. Look for broken teeth or signs of excessive wear. Consult a mechanic if you notice any damaged components.

Install the new gasket by attaching it to the differential and holding the differential cover in place. Hand-tighten all bolts.

Tighten the bolts down one at a time with a socket wrench. Start with the lowest bolt, then go to the highest bolt. Alternate the bolts you tighten in a criss-cross pattern to evenly seat the gasket.

Remove the rubber fill cap and fill with the appropriate weight gear oil. Fill until the fluid level is just below the fill cap hole. A small bead of oil will run out of the hole when the differential is full. Replace the cap when finished.

Items you will need

  • Socket wrench

  • Oil bucket

  • Gear oil

  • Gasket

  • Screwdriver

  • Scraper

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.