Written By: dixie_boysles
Discalimer: Neither I nor this site takes any responsibility in any damage or actions resulting from this . When performing this, you are doing so at your own risk
In this how-to I will be showing you my method to replacing the gear oil in your rear differential. There may be other ways, but this is the way that I found best. This was for my 04' Lariat with 3.73 Limit Slip. The same steps go for a Ranger.
- Gear Oil ( quantity and specs manual calls for)
- 1 Tube of TransX Friction Modifier (for people with limited slip only!!!)
- 1 tube of RTV Sealant (The gray kind if possible)
- 1 Can of brake cleaner
- Old Rags
- 3/8" Drive Ratchet
- 1/2" Socket
- 1/2" wrench if needed
- razor blade or gasket scraper
- Oil Drain pan
- Wear old cloths as you dont want gear oil or rtv sealant on you
- I wore medical gloves to keep the smelly gear oil off my hands (that stuff stinks)
- you should always loosen the fill plug before you start the job to make sure the plug will come out. You'll be in a tough situation if you pull the pan, drain the fluid, re-install the pan then find out you can't get the fill plug out.
Put truck in park and apply brake. Place Oil catch pan under rear differential
Using the 1/2" Ratchet or Wrench, start loosening all of the bolts
I took them all out but the top Two, used them to hold the cover so it wouldnt fall for the next step.
Once that is done, it's time to break the seal. Using a combination of the screw driver and the hammer, try to pry away the bottom of the cover from the axle. dont force too much in one area.
Then oil should start to drain
When it drain all the oil then go ahead and remove the remaining two top bolts.
Use the razor blade to clean both mating surfaces on the axle and cover
Use brake cleaner to clean the gears and the back of the diff cover
Once both surfaces are clean, apply RTV sealant around all the holes and a good solid bead around the perimeter of the cover
Put cover on and hand tighten all the bolts, let RTV dry for an hour then tighten completely using a cross bolt pattern similar to tightening lugs for wheels.
Using the 3/8" drive ratchet, loosen oil drain plug
Once loose, begin filling. I mixed my friction modifier with a qrt before putting it in. fill until the oil is level with the fill hole. Plug the hole. Done.