Rear Differential & Transfer Case DIY
 

After getting my Royal Purple 75W90 Synthetic Gear Oil yesterday, my uncle, cousin and I went ahead and changed out the fluid in the rear differential and the transfer case. We later did the front differential and transmission, which I will talk about in a separate thread.

Royal Purple won the who can import to Mexico sweepstakes, but I also tried to get Liqui Moly and Mobil 1 gear oils, but no dice.

2 bottles of the 1 quart (.946 liters) is all you need to do both the rear differential and transfer case.

This was one disgusting job.

I wanted to add that I have 107K miles on my RX.

For tools, a 3/8ths or 10 mm hex wrench for the rear differential and a 15/16ths or 24mm bolt adapter on to a torque wrench for the transfer case will do the job.

Note: over the years I have done this a few times and these threads below might be more helpful especially on problem areas I have encountered.

See:

Drain and Fill #2, https://www.clublexus.com/forums/rx-...er-case-6.html (starting at post 78)

Drain and Fill #3 https://www.clublexus.com/forums/rx-...r-case-10.html (starting at post 141)

Let's start with the rear differential.

I would highly recommend you start off by opening up the fill plug, which is located just to the left of the passenger side, rear right wheel.

The service manual does a decent job showing the locations.

Another picture of the same area taken a little further back.

This is where the fluid exits.

This is another shot of the area. Antonio Jr. and I tried different hex wrenches until we got the right one as in our shop everything is scattered all over the place.

Here comes the old fluid. This fluid was a lot cleaner than the transfer case fluid we will see later.

Here is the old fluid on my finger. Didn't have any bad smell of any kind.

This was the disgusting part of the rear differential drain. Look at all the garbage on the plug. There were metal filings all over this thing along with a lot of gray residue. I had to clean it off first with a rag then used some cotton and some thinner to get the rest of this gunk off.

We had to use a long hose to get the fluid into the rear differential. Somebody else was using our funnel at the time (you will see in the transfer case photos how we did it a little differently up front), so we simply attached this hose after cutting off the top of the Royal Purple bottle and started squeezing away.

Please note that when the rear differential calls for .9 liters, this is really true. The Royal Purple bottle is .946 liters and Antonio Jr., my cousin, was holding the hose into the hole underneath, while I squeezed. Once the bottle was empty, he pulled back the hose only to find out a little was still dripping out of the filler hole, that .046 I would assume. The same thing happened with the transfer case. We just waited a few seconds until the excess cleared and replaced the filler plug.

This and the transfer case are definitely two person jobs, unless you are super careful and patient.

The transfer case also takes .9 Liters of the Royal Purple gear oil.

You first want to remove the filler plug near the front center of the vehicle, at the front of the propeller shaft.

A closer shot of the filler plug.

The hexagonal nut is the drain plug. Also notice that welded exhaust pipe. That is where that accordion-like piece used to be that some of you have had issues with.

The service manual I don't think does a decent enough job of explaining the transfer case.

That is Antonio Jr, my cousin, watching the transfer case fluid come out.

Here is a side shot of the fluid draining out.

This is what came out. It wasn't as clean as the rear differential and boy did it ever smell. Several of us nearly vomitted just walking by this stuff. Smelled like eggs that had been out too long. Not overpowering, but just if you took a normal breath as you passed by.