Isentropic

Thanks for the suggestion. I am placing an order for 4-7 qts. of WS fluid.
Just not looking forward to taking off the underbody covers again :-(
Those are always a pain to take off for service.

lexsc4

Better safe then sorry with a huge repair bill.

Jack

Isentropic

I just attempted the rear differential fluid replacement and it went quite well. Thank you very much! I was just a bit surprised by the level of rust on the plugs and overall underbody components.

VtecGSR95

In your location, I wouldn't be surprised.

jamieZ

EVERY vehicle driven in the winter MUST be rustproofed. I don't care what kind of vehicle it is, they all rot without some type of protection. Jamie

jmu2004

I knocked this project out this weekend.

Let me just say, USE A PASS THROUGH socket on the front drain bolt. I tried a 24mm crowfoot, and the damn thing nearly destroyed the drain plug. The plug is clearly made for a socket as there is a small indented area around the plug made to fit a socket. The crowfoot was far too wide/big for that indent, causing me to only be able to torque on the outside edge of the bolt and rounding off the outside edge. I then went to the store and purchased a pass through socket set, which had a small enough footprint to fit b/t the plug and the exhaust pipe. Also, liberally apply PB Blaster the night before trying to break plug free. After 160,000 miles, it was STUCK big time.

I used Mobil-1 75-90. Pumping it back into the fill hole can be a bit messy, so be ready for that.

The old fluid was ok after 160,000 miles, but it was very thick and worn. Lexus is probably right that you don't NEED to change it, but if you're planning on keeping your RX for over 200k, do it. Same with drain and fill every 50k on the transmission.

I have noticed a marked improvement in drive quality. No more surging and the drive quality is right back to where it was when new. Fuel economy has been the biggest difference though....easily 10-20% better now.

RedGemini

I just finished this job. It was rough, and the rear diff fluid was horrifying. It's obvious they haven't been changed in 135k miles. The rear was very thick, and pure black. The transfer case was pretty bad, but nowhere near as bad as the rear diff. I had a real hard time getting the 10mm in the plugs. They were caked full of debris/rust that I had to keep scraping and pounding to get it broken up. The fill plug for the TC was some trouble. Again, I had to keep scraping and banging to break up crud, and even used some corse sandpaper to clean around the tight spot. I probably spent a solid 3 hours on the job. At least it'll go easier next time.

numbafree

So I just checked and changed the rear diff fluid. I bought the 05 rx330, Feb 2016, I am the 3rd owner. 164k miles. Like any good DIY gal, I checked the rear diff fluid (all the fluids actually). it was black and thin, my guess is 50k on cheap tranny oil.
I am a redline gal, so I put a little under a qt of redline 75-90 GL-5, and since it's been 15k miles, and that's the change interval, I checked today. I needed to rotate the tires and change the engine oil. Well, it was clear, not tinged red like new oil, and the drain plug was sludgy black. definitely not dirty, so I am guessing I can go to 20k between changes for the rear diff and the transfer case, most likely 25k miles. I changed it cuz I was under the car and had the fill plug loose, might as well. 20 minutes for me, if I didn't get forearm pump from the manual el cheapo pump I had for the new oil, lol. I'll change the transfer case fluid soon, just tapped out after pumping a 1qt into the rear diff.

Kyote321

I did transfer case and rear diff at 120k on RX330. The front had some metal film on the magnet, but the rear was thick sludge.

replaced with Mobil 1 75-w90

thinking it will need to be done again at another 30k. never seen so much sludge metal on a magnet!

24mm on a 1/2" drivesocket for the top of transfer case just fits.

ordered a 24mm crowfoot for the bottom but as others noted, it slips. but, the 24mm socket can be used on the bottom with a pipe wrench to pop it

the crowfoot then did come in handy to replace the drain plug and new crush washer

markgil1

Great write up.
I recently bought a used 2006 RX 330 and have a lot to learn

dcdyd

Should this be similar for 08 AWD ?

dcdyd

Over the weekend, I did this for my 08 AWD. At 100K, the liquid comes out as brown and definitely needs to be replaced. Note that I only towed a U-Haul 5' trailer for moving and drove about 1300 miles.

Couple comments here which may be useful for anyone who wants to try.

1) For the Transfer Case drain plug, I just used normal 24 wrench to break it. It is the best you use WD40 overnight. It is doable.
2) For the rear differential, the fill plug is heavily rusted and I couldn't put 10mm hex bit in at the beginning. I almost thought that it uses different size of hex bit. You need to clean it first.
3) All four plugs use same gasket which is widely available from ebay. The part# is 12157-10010.

Buffalo777

THANK YOU for your step-by-step instructions. I found them really helpful!

Are you absolutely sure about 100K km fluid change interval for transfer case and differential?
Service manual suggests 48K km, but I know it is biased towards visiting Lexus dealership MUCH MORE often than your RX330 really needs, to make them money :-)

What is your PERSONAL experience with 100K km fluid change interval for transfer case and differential?
What do you think about MOBIL 1 GL5 75W90 fully synthetic fluid as an alternative to GL5 85W90 conventional fluid, which recommended by Lexus?
Mobil 1 tech specialist told, that despite GL5 75W90 is fully synthetic, its "contamination" occurs at the same rate as with conventional GL5 85W90.
What do you think about this statement?

Thanks again, and good luck with everything! :-)

Chapp

I've spent over an hour looking for these part numbers.
One question. When I go to ebay to check compatability, it says not for my 05 RX330. Is this due to Ebay thinking it is for the enigine oil drain plug?
Also, what size are these washers? I already have some 18mm for my 09 civic. I didn't know if they were the same?
Thanks again.

dcdyd

I use www.lexuspartsnow.com to confirm that the part number 12157-10010 is for my 2008 RX350.