According to my Toyota shop manual for the All-Trac,  "ATF Dexron II" is to be used in the rear differential.  This is clearly a mistake; it should be some sort of multi-viscocity gear oil.  When I asked my local Toyota dealer, he said just to use any 80W-90 oil, and that they no longer offer any Toyota-branded oil.  But can I use a synthetic oil instead of a petroleum-based product?  The rear diff has no apparent leaks, but changing that oil is long overdue.
Unfortunately, I can't find any record of it ever being changed, and I think my All-Trac diff is way overdue for an oil change, especially I use the car on long severe-driving trips out of the country.

Changing the rear diff oil is cheap... since you only need 1L.

At this point the $$ is not a mater !

Synthetic blend is not a "big deal" in a Corolla wagon. I don't have this opinion for the engine... and for my Landcruiser diffs because they work much more then the Corolla diff.

When you will make the oil change and you find it very dark ou grey, make sure you change it again after 100km or so... you will clean the internal part this way.

Lucas additive or other good brand is not bad too.

My opinion !

Thanks, David.  The rear diff oil is stil yellow color, but I plan to change it anyway; I want to run [URL]["http://www.Auto-Rx.com"]Auto-Rx[/URL] in it, and then drain it again.  When you said, Lucas is not bad, which Lucas product were you referring to?  

Quoted from datsa

Thanks, David.  The rear diff oil is stil yellow color, but I plan to change it anyway; I want to run [URL]["http://www.Auto-Rx.com"]Auto-Rx[/URL] in it, and then drain it again.  When you said, Lucas is not bad, which Lucas product were you referring to?  

Lucas Heavy Duty Oil Stabilizer - http://www.lucasoil.com/produc.....y%20Oil%20Stabilizer

I'm going to bring up this old thread because I've got a few questions..

I recently changed my transmission fluid with some economy brand gl-5 80w90 gear oil. I didn't know it was gl-5 at the time, so now I'm looking for some gl-4 oil, but I can't find any... at all.

I looked online at redline and amsoil and all their stuff is gl-5. I looked at my local stores and everything is gl-5 or 6.

Where are you guys getting GL-4 gear oil? I want to change it out before my synchros are gone!!

I personaly don't car about the GL-4 or 5.

Read that : http://wiki.answers.com/Q/Whats_the_difference_between_gl4_and_gl5_gear_oils and http://www.api.org/certifications/engineoil/pubs/upload/1560.pdf

Redline MT90 is a GL4.  It  is supposed to be excellent.   I would use that but I thought we were supposed to use GL5, not GL4.

Hate to bump this, but now that I have my repair manual I'm seeing the exact same thing, that you're supposed to use ATF DEXRON II in the rear differential.  So, if I'm about to change out this oil, should I go ahead and use the 80w-90 GL-5 oil that I bought two gallons of?  (Most of it is for the transmission / transfer case.)

Quoted from Rogue

Hate to bump this, but now that I have my repair manual I'm seeing the exact same thing, that you're supposed to use ATF DEXRON II in the rear differential.  So, if I'm about to change out this oil, should I go ahead and use the 80w-90 GL-5 oil that I bought two gallons of?  (Most of it is for the transmission / transfer case.)

Hey Rogue: I think this is a mistake. It doesn't make sense to use ATF in the rear diff. I never did use ATF Dexron II, but just went with a quality 80W-90 gear oil.  You can check out websites for boutique oils like Amsoil http://www.amsoil.com and they recommend the same thing.

You should be fine with the 80W-90.  I changed my rear differential oil about six months ago and used 80W-90 GL5, and I have had no problems.