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Picture of How to Change Differential Fluid

I will be demonstrating and giving examples on how to change the differential fluid in an axle on my dad's 2001 f150. Although it is not an everyday occurrence, changing the differential fluid in a vehicle is a normal replacement done on types of equipment. Weather on a big rig, tractor, pickup truck, or another vehicle at some point in their life they should have their differential fluids changed to increase their life and reliability.

The differential is what transfers the motion of the transmission or transfer case to the wheels on the ground through gears and axles inside the differential. Depending on the drive of the vehicle, whether it be a rwd, fwd, 4x4, or awd, the differential can be located in the back, front, or in both front and back.

Many manufacturers have a specific amount of time or miles that they would recommend changing differential fluid. Many times on highway vehicles it is somewhere around the 150,000-mile mark. Not everybody changes this as it is not a “necessity”, however like anything over time it becomes contaminated and breaks down, especially if the vehicle has sat for a long period of time and the seals have gone bad on the differential cover.

Step 1: Get Your Supplies

Picture of Get Your Supplies

Before we begin working on draining the differential, it would be wise to look up in the service manual for the vehicle how much fluid the differential takes. If the information cannot be found, looking it up online is the next best thing as long as it is from a reliable source. After finding the given information needed, go to the nearest store and buy the gasket for the vehicle and the differential fluid of personal choice. I would recommend driving the vehicle to the store if at all possible to allow the fluid to warm up in the axle and flow out much easier when removing the differential cover. Weather being brand specific or trying to buy the cheapest fluid possible, it’s all personal preference. Many times true differential fluid cannot be found, a common replacement is to use Automatic Transmission Fluid in its place. It would also be a wise idea to pick up some brake cleaner as well for cleaning the differential cover later on.

JAMESM4661 year ago

One suggestion for anyone doing a differential service: remove the fill plug FIRST.

You don't want to have the unit drained, cleaned up and the cover reinstalled only to find out the the fill plug is frozen and cannot be removed with hand tools. If that happens, you cannot drive the vehicle and it must be flatbed towed to a repair facility.

Don't ask me how I know.

Two things...

1. Never use Automatic transmission fluid unless it is specified!!! This differential uses gear oil. Gear oil is readily available at your local auto parts store and sold in varying weights like engine oil. Also if the differential is equipped with traction clutches an additive is also required.

2. This differential was not made with a cover gasket. It uses a quality sealant.

Other than that the write-up was accurate for this procedure.

Hard to find diff fluid? Which auto parts store are you shopping at? Secondly, ATF is more of a hydraulic fluid, not a lube like the gears need. Diff oil has a different viscosity than ATF. Its best to use what OEM recommends.

Swansong1 year ago

That's a good thing to know how to do :)