98Nav400

***Important disclaimer= I am a mechanical idiot. Feel free to comment on how to do this better. I think that if I can do this anyone can easily. Here is what I did:

I am coming out of warranty and the diffs and transfer case fluids are due @ $350ish including oil change from the dealer. I didn't do them at 30k and figure 45k is probably time. I should have taken pics but never think about that.

Oil Change:
7 qts Mobil 1 Syn 5W30: Costco=$24.99/6 + $6.09 for the 7th
Oil Filter From Toyota Dealership: $4.45
Oil & Filter Total: $35.53 versus $85 for Non-Syn at Dealer

Diffs/Transfer:
7 qts Mobil 1 75W90 Syn Gear Oil = $62.23 at Autozone.

Changing the oil: Really Easy
1a)Warm up Engine
1b) Remove front skid plate ~ Remove 4-12mm bolts, 2-10mm bolts, and 1 plastic push pin. It hooks in the front so look for the clips and tilt down, push up, and pull out. Takes 5 minutes being careful
2) Remove plastic cover over oil drain bolt. Mine was missing thanks to Lexus not putting it back on. *If you are doing the diffs and transfer case you have to remove the center skid plate as well so skip this step and just remove the skid plate 4-12mm bolts.
3) Remove drain bolt and let oil drain.
4) Replace drain bolt.
5) Remove oil filter its very easy to find and remove. It would be worth buying one of those cheap oil filter adapters that hook onto a socket wrench if you were going to change your own oil regularly.
6) Replace filter with new. Put a little oil around plastic gasket on filter first and only tighten 3/4 turn past snug.
7) Refill oil, 6.5 qts start, check for leaks and replace skid plate.
Total Time:45 minutes or from starting to assemble tools and being completely done, tools put away.


Differentials/Transfer Case
1)For diffs/transfer make sure you warm up the car thoroughly by driving it around for at least 15 minutes. **Also important note. Always remove the fill plug first. If you get the drain bolt out, drain, and can't get the fill bolt off you are screwed as the vehicle will have to be towed. No fluid = No go.

2) Get the vehicle up as high as you can, either by ramps, jacks, whatever. You can do it with little room but more room makes it exponentially easier.

2)Remove both skid plates

Rear Diff.
These are 6pt 24mm bolts. Fill is on the back, drain is underneath slightly to the pass side.
1) Remove fill bolt.
2) Remove drain bolt
3) Let drain, clean off bolts. Drain bolt is magnetic and will probably have some shavings on it.
4) Replace drain bolt.
5) Put in new fluid through fill bolt. This is a pain in the ***** and you will likely swear a lot unless you have a pump ~ I don't. It is pretty tight so I put a small piece of tube on the end of the bottles and the best I could tilted the bottle up and pushed the fluid out of the containters. It should take about 3.15 qts. It is full when fluid starts to come back out of the fill hole.
6) Replace fill bolt.

Transfer Case:
These are also 24mm bolts. They are on the back side of the transfer case. Upper right is fill, lower left is drain. It seems that they are the only 24mm on the case but not sure.
1) Remove fill bolt.
2) Remove drain bolt
3) Let drain, clean off bolts. Drain bolt is magnetic and will probably have some shavings on it.
4) Replace drain bolt.
5) Put in new fluid through fill bolt. Not as big of a pain, but still sucks. Only about 1.5 qts makes it much nicer. When it spills out the fill its done.

Front Differential:
This one is different. These are 10mm Allen head bolts. Definatley buy some Allen head sockets if you don't already have some. There is no way you are going to "break" these bolts with standard allen keys. The fill is visible from the front, the drain is lower on the drivers side of the diff. They are pretty clear which ones they are knowing that they are 10mm allens bolts.

1) Remove fill bolt.
2) Remove drain bolt ~ mine was on SUPER tight. Make sure you use an extention so that the socket is going into the bolt straight on. If you try to put it in without an extention you end up hitting some other body piece and end up in the bolt crooked.
3) Let drain, clean off bolts. Drain bolt is magnetic and will probably have some shavings on it.
4) Replace drain bolt.
5) Put in new fluid through fill bolt. This one is the biggest pain yet. It is really tight. I had to snake the bottle up and though the engine area to get enough of an angle to push the fluid in. 1.5 qts again. When is comes out the fill you are done.
6) Replace fill bolt.

*Super Mechanic Step-Take the car for a quick drive. Open up the fills plugs again and add until it seeps out. For me only the tranfer case took any and it was only a marginal amount so this step maybe a waste of time. If you used just over 6 qts of the gear oil you should be fine.

Check for leaks, replace skid plates, go take a shower since you smell like oil by now.

This trans/diffs took a couple of hours, much of that was trying to break the front drain plug and pushing fluid back into the cases.

Total time for both was ~ 4 hours. Mechanically totally easy for me as a non-mechanical person, some of it is just physically bothersome as you are crawling around a lot, screwing around with oils, etc.

All in all changed all of the fluids with full synthetics (better than Lex does) for less than $100 and 4 hours time.

I have attached a couple of PDF's to help show where the drain fill plugs are. These are for a Tundra but the locations and bolts are identical. It is much easier to see on the actual parts than in these diagrams. Ignore any quanities listed in the PDF's as our vehicle is different.

98Nav400

Transfer Case:

AGAIN IGNORE FILL QUANTITY. Our vehicle takes about 1.5qts.

98Nav400

Rear Diff.

malmon

This is great, although I have less than 2K on my GX, I am ready when the time comes to change the fluids. Thank you for sharing.

cmarshack

Great write-up! Thanks!!!

When you are done you can also re-set the Maintenace light:

"Turn car to the 'ON' position in the ignition
Cycle through the Odometer so that you are on Total miles, not Trip A or B.
Turn car off
Hold in Odometer button while turning car back to ON.
Keep holding until the Maintenance light flashes and then goes off for good."-G-Man

kphu

iTrader: (8)

great write up! Thanks for sharing. I'm coming very close to 60K on my vehicle so its time to do the fluid changes.

I was at KMART last night looking at toys for my daughter's schoolmate's birthday that's coming up. Of course I couldn't help but to take a gander throught their automotive section and saw a fluid pump for $11. I'm going to have to go back for that now.

Lexmex

Nicely done. I never found it too hard (if you had the right equipment) to do this on my RX300, but it is something that is well worth the effort and saves $$$.

-darren-

nice work on the write up

atokad

I was just looking for some help on changing the oil on my GX and came across this thread. Nice write up on the diffs.

Noticed this price quote from 2008! Obama, I mean Oh boy, how prices have changed!
Sam's Club today, 6 qts Mobil 1 5w30 - $37.99.

stiles_s

Thanks for the post!
quick question: we have a limited-slip rear differential, don't we?
If so, is there different lube specified for the rear diff when compared to the transfer case & front diff? I know that Redline has "limited slip" and "non limited slip" versions of their 75w90 gear oil.

Thanks,
Scott

tzh2231

This got to be typo, is not it? I've never seen any 24mm socket in a mechanics socket set.
I think you mean >>>> 14mm <<<< rather than 24mm ?

wolfalp159

Great write up. In terms of filling the oil I have used an enema bag and it works great. You can hang it up from a door and run the tube under the car. It makes filling much faster.

Matsui

When the dealer changes differential fluid (front and back), do they also change transfer case fluid as part of the service or do we have to specify that separately?

danmm7

Based on the maintenance receipts i got from the previous owner of my GX, the transfer case fluid was always a separate item. I see the differential fluids replaced as one service and the transfer case fluid as separate procedure, with separate price tag next to it.
Not sure if every dealer/shop does it the same way. Some dealers have "packages".

infinirx

This is great thank you! I am going to refer to this when I get it done soon. It's time anyways.