Hello everyone! I'm newly registered here but have been reading and learning from the this forum for many years. I have a 2009 RX350 AWD. I bought it from the first owner in 2014, it has 114,000 miles and I plan to keep until it causes me significant grief. So far, I've only had to do general maintenance and have the power steering pump replaced at 97k.

I'm about to have the transfer case and rear diff fluids changed, for the first time. I've read through many threads about this and see that the "lifetime" fluid is not really a thing. Though I'm really late to the party, I'm going to have it done and hope for the best. My manual says to use "hypoid gear oil API GL-5, SAE90 (if below 0 degrees F: SAE80W or SAE80W-90)". When I enter my car info on auto parts sites, it turns up 75W-90 and 80W-90 of various brands. I also saw a post that referenced an article about gear lubricant standards having changed in 2019, indicating that what my manual calls for may not be the same as current standards. So, I have no idea what to gear lubricant to buy. Here are my questions:

1) What brand/type have you tried and what was the outcome over time?
2) Do I need 2 different types, one made for my limited slip diff and a non-LS lubricant for my transfer case?

Any recommendations will be greatly appreciated!

 

Our cars don’t use limited slip diffs, the 1999-2000 RX300 did as an option, but it was a Torsen differential without clutch packs so it uses regular fluid. You could swap that unit onto your car if you can find one, I have been sent 4 open diffs so far. Like the 01-03 Highlander, us 07-09 RX owners have a viscous coupling transfer case, this uses regular fluid as well.

I have been running synthetic non-LSD 75W90 GL-5 Redline gear oil in my Highlander’s t-case and rear diff for over a year now with great success. On my RX, I run the same in the front, but just used some of the Toyota 75W85 GL-5 stuff from work in the rear and it works fine as well.

 

Thanks for clearing that up MattRX, I guess I saw limited slip listed on a website rather than in my manual or spec sheet. For your RX, would you use the Redline for the rear diff, if you hadn't already had the Toyota brand on hand? Or, was there another reason you used Toyota brand for the rear?

 

I used the Toyota stuff as the can was dented and we couldn't sell it to customers, but the Redline stuff is definitely better. I figure it doesn't matter too much what I put in there because I'll be swapping a 1999 RX300 Torsen diff down the road anyway. I would like to add that with 222k miles the fluids were original, the diff fluid looked fine, but the t-case fluid was very dark and disgusting. Synth oil always came out looking cleaner so I try to use it everywhere I can, except for the trans where I use OEM fluid. In the power steering, I also use synthetic DEX 6 trans fluid vs the factory DEX 3. The pump is a lot quieter on cold winter mornings, and the thinner oil never gave me any issues with leaks or anything of that sort.

 

https://www.youtube.com/playlist?lis...oNRoEnBwQso5Bk

 

I went w/ the Royal Purple 75/90 for the transfer case as well as the rear diff....Since your there, grab a gallon of Maxlife trans fluild as well as a Wix trans filter, pull the pan & clean the two magnets, swap the old filter.....