Changing Differential and Transfercase oil -**LOTS of PICTURES!**

In this write up I have decided to provide pictures and brief instructions on how to change the differential and transfer case oil for an automatic 3rd gen 4runner.

My case is a 2001 4runner limited, all 3rd gen 4runners are similar therefore, these instructions will be the same for other years within the same generation.

I am using Amsoil gear oil, the gear oil you choose will be left at your discretion.

I picked up a pump for the Amsoil gear oil bottle at my local O'reillys. Here is what I picked up, works perfectly for the Amsoil bottle:





I also picked up new drain and fill plugs. The drain and fill plugs are soft metals, meaning they could strip easily. I figured if these were the original drain plugs, I put in new ones with "fresh" metal, per se. Also, some of the plugs appeared slightly stripped due to a previous gear oil change from the original owner.

If you do not replace the drain and fill plugs, I do recommend replacing the crush washers.

A 24MM socket is used to remove the differential and transfercase drain and fill plugs.
A 12MM socket is used to remove the bolt holding the hand brake cable bracket that is running right across the fill plug on the rear differential:



Rear differential:

Remove the bolt holding the brake cable that blocks the fill plug (not pictured), but its location is highly obvious.

Once the brake cable is out of the way, remove the fill and drain plug.

Make sure to have a pan handy to catch the oil:



Once the oil has been drained, inspect the drain and fill plug:



The drain plug has a magnet that catches shavings from the gears. Anything out of the ordinary would be noted here.

No gear teeth or large chunks of metal, just small shavings, which is normal.

Thread the new drain plug, ensuring that the crush washer is installed.

Using your handy hand pump, stick the end of the tubing into the differential and start pumping away:



Pump fluid into the differential until you see a steady stream of gear oil flow out of the fill hole:



Plug it up and you are done with the rear differential. Make sure the crush washer is on the fill plug.

Now we go to the transfercase:

Locate the drain and fill plugs, drain plug:



Fill plug:



Remove the fill plug first, then the drain plug:



Once the fluid has been drained, install the new drain plug and start filling the transfercase with new gear oil.



Again, you will know when the transfercase is full when you see a nice steady stream pour out of the fill plug.

Set the fill plug, and you are now complete with the transfercase:



Now, we will move on to the front differential. In order to access the drain and fill plugs, the skid plate will have to be removed.

Once the skid plate has been removed, you will notice the fill plug on the front of the differential:



The drain plug is below:



These plugs require a 10MM or a 12MM hex to remove. Please confirm sizing, I needed to use a 10MM hex for both drain and fill plugs. Some have used a 10MM for the fill and 12MM for the drain.

Remove the fill plug first (not pictured), then remove the drain plug.

Removing the drain plug:





Comparing the drill and fill plugs with the new set. Again, check for any abnormal shavings on the magnet of the drain plug.



Once the front differential is fully drained plug the drain and proceed with filling:





Again, the differential is full when you see a steady stream of differential oil flow out of the fill hole.

Once the differential is full, set the fill plug:

 

Finally got these pictures working.

 

Thank you!

 

Great write up, I’d throw in a suggestion to upgrade the Lexus diff plugs, which will change your Hex plugs on the front diff to 12mm plugs you can get a socket on. Far less strip hassle

part numbers: 90341-24016 & 90341-18060

 

Excellent write up, I'll add,make sure you can get the fill plug loose first before you drain it. Had an issue with this once

 

Great post. Thank you for your efforts in posting it.

 

On the rear diff anyway, you can pretty easily empty a quart bottle directly into the hole if you cut the nozzle just right, big enough so it empties quickly and not so big that its too short! Been a while since I've done the tranny on my 5 speed so I don't remember if it can be done there too.

 

Part numbers for replacement plugs would complete this helpful DIY.

 

Great write up! I can smell these pictures. LOL