mcenteep

Just did both on mine. Easy job. Just be careful when removing the fill and drain plugs not to booger-up the hex.

Millarduck

Like golferjack, I just went through the 2021 Warranty and Service book. There is no scheduled maintainance required for the differntial on the hybrid. It only says on Page 71:

Rear Differential
Oil Check level and condition of oil and inspect the rear differential assembly case for signs of leakage. (The rear electric motor/generator does not require periodic maintenance.) Any service that requires inspecting or replacing rear differential oil should be performed by a qualified technician following procedures in Lexus service and repair publications. Please refer to the important safety precautions on the inside front cover of this booklet.

Seems to imply that you only change it if it is leaking. Keep in mind that motor only kicks in when there is slippage in the front drive wheels. Reviews I read on the 350 and 450 say the 350 has a better AWD system because you can lock it into AWD, an option you cannot do with the CVT using 450h. So I can imagine the 350 with the auto transmission and a transfer case (not on the hybrid) has a larger differential and sees more "wear" than the hybrid independent motor in the back which is controlled by the computer and not the driver.

My Jeep dealer told me that lifetime fluids mean they last the life of the car where the cost ot repair (transmission) exceeds the value of the car. He said it with a wink and smile, but that's what manufacuter's mean by lifetime.

DaSyce

iTrader: (3)

The rear Hybrid motors appears to activate constantly during normal driving. Both in low speeds and at highway speeds.

HAILHYDRA

but where did you buy your Tom’s racing lip for your 2IS?

CaptStumpy

Seeing metal on the drain plug confirms there's junk in the fluid. It needs service.

tempestv8

If the fluid is lifetime, why then does it turn so dark after extended usage? I believe this is an indication that the fluid is breaking down due to heat. I would expect the breakdown from continuous heat and cold cycles is detrimental to the lubricity of the fluid. Not sure why the USA and Canada vehicles do not specify a fluid change interval, but on the Australian service booklet, it does specify a fluid replacement for the RX450h on the rear section of the booklet under the severe usage section.

richard203

iTrader: (1)

im asking this because i told the advisor to do trany and diff fluid drain and fill and he ask me is my car have awd and i say yes then he say u want to do front diff too? i say sure. im asking here because i saw the tranny fluid thread no1 talks about the front diff only the tranny and diff. let me know thanks

Millarduck

If the Lexus service advisor asked you if your 450h is AWD (they all are), then, run don't walk away. Never go back because they hired a moron as a service advisor it makes you wonder who is taking wrench to the car.

jollick

From Edmonds:
2016 Lexus RX 450h models
The 2016 Lexus RX 450h is a five-passenger midsize crossover SUV available in front-wheel- and all-wheel-drive versions.
https://www.edmunds.com/lexus/rx-450...ive%20versions.

tempestv8

Not sure why that service advisor made a distinction between transmission and front diff, as if these are two separate things on the 4th gen RX450h. The CVT gearbox (transmission) happens to also be the front differential, as it is effectively one unit. Which means that there is not two separate lots of fluids. The service advisor is making it sound like there are two separate fluid changes, one for the tranny, and one for the front diff. But it is the one and same thing.

For the rear differential, that's a separate fluid change there. At least in Australia, all 4th gen RX450h are AWD. The only 4th gen RX in Australia which has just front wheel drive is the RX270 (pure ICE, not hybrid)