Lexmex

The area with the yellow circle uses ATF, while the blue square uses gear oil.

TunedRX300

I think you quote me wrong, as Lexmex mentioned, people here use front differential and transfer case interchangeably. Please go back and read my post carefully, you will find that I never stated front and rear differentials uses ATF.
For me, I call the yellow part circled by Lexmex transfer case, it shares ATF with the transmission, you pour the ATF from the tranny dip stick and ATF will finds its way to there.
Also the only way to make sure is to do the draining and filling yourself, it is not hard to tell the difference between ATF and gear oil. No one ever service the transmission, transfer case, differentials but me, all fluids that came out of drain plugs came from factory fill, it is actually pretty simple to pour in the type of fluid that came out, no matter how one calls certain component.

wing0

When should the front and rear diff oil be changed?
I'm at 40000km right now and haven't changed that yet.
I just finished another tranny oil change...and since it's like winter here. I really don't want to do the diff oil change until summer and probably another 5000-7000km later. Is that acceptable or I should have the diff oil changed sooner.

bob2200

I'd wait for the warm weather in Ontario, unless you're driving down to Florida anyway this winter; like so many others from Ontario.

Lexmex

You still have a young vehicle. That translates out to about 24,000 miles. If I were you, I would probably change it around 50K or so (I would have done this in hindsight) and go with a synthetic 75W90 (the stock was an 85W90). I use Royal Purple (came as recommendation to me from GS owners and my reading), but Mobil 1 75W90 gear fluid works just as well for many (TunedRX300 can give a great comment on this). Redline is also a good option. However, I would not use the stock again, which I think was a Castrol.

I didn't change my original from the factory fluids until after 100K. In the service manual, the first time it is evern referenced is at 15K miles. FWD owners don't need to worry about this, just AWD.

Gear fluid is probably the most durable fluid that goes into our RX300s. What you may notice after you change it out is that the gear changes are smoother, for me this was especially noticeable in 2nd to 3rd where when I would be at the track (last gear change before the finish line) it didn't have any clunk or noise as before, it would just change over.

wing0

I am noticing that 2nd to 3rd gear change is rough compared to all other transitions. Could this have something to do with the gear oil or the diffs?

I've drained the tranny oil at 32000km and 40000km, which is about 5L each time. Just trying to keep that Type IV in decent shape.

Lexmex

Your vehicle is still young, however I would have to actually drive it to notice the 2nd to 3rd transition.

khmiller

To LexMex:

17.5 yrs later and still your post helped someone. Having never changed the rear diff oil or the transfer case oil on my '03 Highlander Ltd AWD w the 1MZ-FE and 4ATM, I got fatigued and wasn't paying attention and ended up opening that ATM 10mm hex socket plug instead of the 24mm bolt head plug drain on the transfer case. For the life of me I just could not quite figure out what I had done. And had missed the chance to measure the volume of what came out. Toyota parts schematics basically do not show that hex socket plug, only the drain plug in the transmission pan proper. And Toyota throws around "transmission", "transaxle", "transfer", and "differential" somewhat non-succinctly to say the least. I don't think that "extra" drain is even present on the '04 and later 1st gen highlanders w the 3MZ-FE and 5ATM, so lots of you tube videos just were not that helpful in identifying that drain plug.

So; Much Thanks for a good picture that answered my dilemma.