450h differential fluid
Separate section addresses transmission eCVT fluid.
All fluids breakdown.
I’m just a little surprised to hear that the factory service guides are inaccurate about serviceable parts. As the 2017 RX450H Maintenance Schedule also prints that that the rear differential is a serviceable item. Requires fluid inspection ever 30k, and recommends replacement if vehicle is used for towing.
I would like to have it replaced at 45k. I would expect the highest degree of wear to occur early in the units service life. I can only imagine the next highest degree of wear would occur due to a viscosity breakdown of the fluid.
I would expect that replacement of the fluid would serve as preventative maintenance. Thoughts?
Last edited by DaSyce; Jul 28, 2021 at 05:15 AM.
I am not a mechanic so I really know nothing about modern transmissions (CVT or otherwise), but it just doesn't feel right to assume it has lifetime fluid. Aside from the idea of the fluid gradually breaking down, it will also accumulate particles from normal wear. From just a pure logic perspective, I would think anything with gears washed in lubricating fluids is going to have wear (otherwise the lubricating fluids wouldn't be necessary), which implies the lubricating fluids are going to have metal particles suspended within as the fluid ages. Those particles along with the gradual breakdown in viscosity suggest the notion of "lifetime fluids" is questionable. So yes, I agree with your leading question you used to create the poll - even though my "opinion" is based on pure conjecture as I really don't have the knowledge to reach an informed conclusion.Anyway, my 450h is only a few months old so it will be a long time before I have to worry about this, but I have wondered if owners of hybrid transmissions should have the same concern as those vehicles with standard transmissions. Look forward to hearing where this discussion goes...
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Same principle difference for your year except that the front fill plug - TO BE RELEASED FIRST! - is on the wheel side of transmission.
You do not have CVT. Toyota called it CVT for registration purposes in the US. ATF is SPLASH LUBRICANT only and, as such, is no subject to hydraulic stress and wear. You surely welcome to replace it, I did mine on HiHy at 50K miles just for the ****s and giggles, but I like doing such things and have car lift. It is super easy drain and fill. Otherwise, it is indeed a lifetime fluid. I know of a guy who owns TCH with all original, closing on 300 000 miles.
Last edited by nicnac; Sep 3, 2021 at 01:26 PM.
https://www.youtube.com/watch?v=I1fP-RKsqG0
https://www.rav4world.com/threads/20.../#post-2714597
https://www.rav4world.com/threads/20.../#post-2714597
Engineering is not up for grabs by forum "professional engineers "who know the square root of FA ,.....................
Last edited by nicnac; Sep 4, 2021 at 01:10 AM.
Engineering is not up for grabs by forum "professional engineers "who know the square root of FA ,.....................
Here is what the manual says:
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.
Transmission Fluid
The transmission and transmission
fluid are a completely sealed unit.
Therefore, periodic checks and
replacement of the transmission
fluid are not required, and there
is no dipstick on the transmission.
Inspect the transmission/front
differential assembly case for signs
of leakage. (The front electric motor/
generators do not require periodic
maintenance.) Any service that
requires inspecting or replacing
transmission/front differential fluid
should be performed by a qualified
technician following procedures in
Lexus service and repair publications.
Seems clear to me.
Last edited by golferjack; Sep 4, 2021 at 06:46 AM. Reason: left out information
Here is what the manual says:
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.
Transmission Fluid
The transmission and transmission
fluid are a completely sealed unit.
Therefore, periodic checks and
replacement of the transmission
fluid are not required, and there
is no dipstick on the transmission.
Inspect the transmission/front
differential assembly case for signs
of leakage. (The front electric motor/
generators do not require periodic
maintenance.) Any service that
requires inspecting or replacing
transmission/front differential fluid
should be performed by a qualified
technician following procedures in
Lexus service and repair publications.
Seems clear to me.
There is no way to "check its condition" without actually draining it. To what - fair warning. You MUST open filler plug first as some, as it is VERY torqued, could not, while they opened drain plug and ended with only towable vehicle.
Rear PSD is smaller copy of the front PSD.
In BOTH PSDs, ATF is ONLY splash lubricant and bears NO hydraulic function. Hence, it is nowhere warn out as fast, as regular ATF in regular transmission.
Sure, you are welcome to replace it. It's 2.2 qrt rear, drain and fill and 4.2 qrt front, drain and fill. I care not what manual says, I had identical power train - Highlander Hybrid - done twice and I know the real life capacities. TCH also takes 4.2 qrt. Also had it done twice.
If you can lift vehicle level, there is no point in taking it to dealer and paying them mucho dinero for very simple drain and fill job. All it takes is quality L shaped 10mm hex wrench, cheat pipe for it, or 10mm hex socket with breaker bar, some vessel to catch the fluid and either long tube with funnel to feed ATF from the top in or fluid pump to pump it in to overflow.
CAR MUST BE LEVEL.









