plAythiNG

Hi Guys, thought I sign up and get some discussions going after I just picked up a 2012 Lexus RX450H for my wife a couple weeks ago.

I purchased the online version from eBay for the Lexus Service Repair Manual. I just spent 2 nights reading all through 17,500 pages of it. Firstly. What a terrible service manual. No table of contents was a massive let down.

Anyways the reason why I thought I buy the manual was to get some technical information on how to DIY the front diff/transmission, possible transfer case, and rear diff.

I have had a look at my OEM Owners Manual, and it specifically says there that for the transmission (where I am getting the front diff lives) I am to use only Toyota ATF WS fluid. This I get, but what I dont comprehend is the fact we have to use the same oil for the rear diff... Why is this different to the petrol RX350 for example?

Also, is there any aftermarket transmission oil that anyone can recommend besides Toyota ATF WS? I think I will get it as its reasonably cheap, but always open to alternatives.

Cheers

Clutchless

My other vehicle is a hybrid and I had one other and both of them and the RX have the same procedure to change the front transaxle fluid. First open the fill plug, as you do not want to drain the fluid then find you cannot fill it. Then the drain plug. About 4 quarts will drain out. Then fill it back up until fluid comes out the fill hole and you are done. Same process for the differential and transfer case if you have one. Go to www.amazon.com and get a 6 pack or 2 of MAG 1 full synthetic low viscosity multi vehicle automatic transmission fluid. It is what I am running in both my vehicles. It works as well as or better than WS for less money and unlike WS, it is full synthetic.

The rear differential on the hybrid is an electric motor, not like a normal differential, that is why it takes WS instead of gear oil.

You may want to look in and search the hybrid forum that is next to this one on the list as you questions have been asked before over there. https://www.clublexus.com/forums/hybrid-technology-213/

plAythiNG

many thank Clutchless for the reply. Makes sense for the rear diff using the WS ATF fluid than. I'll have a look at that MAG 1 fluid due to it being a full synthetic, although being amazon and living in australia, the shipping might kill the cost for me...

Am I right the 450h is not a 4wd, so there is no transfer case? I need to wait till i visit my inlaws as all my gear is over there before I can jack up the car and have a look good underneath! I think the 450h only has a transmission and rear diff that requires fluid?

salimshah

It seems the service manual you bought is pretty useless.

450H is offered in two models .. FWD and AWD. May not matter to you much in Australia, but in USA the FWD is predominantly sold in the southern states.

Lexus shares the WS transfluid with Toyota. Price it through Toyota. The capacity is not huge so few $ more for each qt should not break the bank.

Salim

paperthin

I am always interested to hear success stories of non-spec fluids. Thanks clutchless.

riredale

The car is basically a FWD with an electric motor on the rear axle. Rear motor is hardly used unless you want a lot of power. Also if you put the car into snow mode it directs more power to the rear motor than otherwise and it behaves much like a conventional AWD.

We're having a mild winter here in Portland Oregon but last year got hit with substantial snow and ice. Major roads were gridlocked and slippery but my 450h did just fine in snow mode avoiding the traffic by going the unplowed back roads. I did have chains on the fronts, but still.

tempestv8

I found an online workshop manual on the RX450h that shows the locations for the drain and fill plugs.

http://workshop-manuals.com/lexus/rx_450h_awd/v6-3.5l_(2gr-fxe)_hybrid/transmission_and_drivetrain/continuously_variable_transmission/transaxle_cvt/fluid_cvt/component_information/specifications/page_3541/

I plan to replace the Toyota WS fluid every 80,000 kms by myself even though Lexus says its a lifetime fluid.

salimshah

What is magical about 80,000Km? Why not 50,000Km or 100,000Km?
At least in hybrid you get to drain almost all of the fluid. One can not take clues from the non-hybrid transmission discussion.

Salim

tempestv8

I picked the magic number 80,000 kms for two reasons:
1. The Prius forums seem to have derived (from oil analysis) that the fluid starts losing its full properties after about 50,000 miles
2. 80,000 kms (which is 50,000 miles) also happens to be the fluid inspection period for most of Toyota service schedules for conventional automatics using the same WS fluid. Whilst a traditional Aisin auto gearbox is not a real correlation to the RX 450h eCVT transmission, Toyota must know something about their own fluid when it reaches 80,000 kms.

So that's just my two reasons why I chose that number. For others it can be as low as 50,000 kms or as high as 100,000 kms, Eitherway, still better than just leaving it in there for "lifetime".

salimshah

I am not making an argument for for the validity of 'life time'. Just want to learn how this conclusion was made.

Can you please point me to the prius study that the decision was made on.

For RX the milage interval should be less ... , my guess would be 2/3 based on proportions.

Salim

tempestv8

I was researching coolant replacement for the hybrid inverter when I came across the ATF changes on Priuschat.

I didn't bookmark them, so can't give you the exactly link. I tried to look it up again, and found some chatter like these threads:

https://priuschat.com/threads/should...k-miles.122274
https://priuschat.com/threads/transm...-change.88903/

But I can't find the exact thread that I came across, as I wasn't that interested in ATF but coolant at the time. These guys seem switched on enough, so I'm going to take heed of their proactive advice and do the same. Short changing the fluid instead of waiting all the way to the specified service interval should hopefully max out the life of the hybrid drive. I don't have the time to do exhaustive studies for myself. and Toyota WS fluid is relatively cheap in the whole scheme of things.

I have 45,000 kms on my RX450h at the moment, and will attempt a fluid change, perhaps tomorrow (weather permitting) and take some photos of the condition of the fluid.

salimshah

Generally folks get concerned about the color, so dont get startled.

just keep few things in mind:
1. Unlike engine oil, there are no combustion bye products and particles in the transmission fluid.
2. When you replace, you get majority of the fluid out in 450H (unlike 350).
3. Unlike auto-trans there is no heat build up as the fluid does not absorb the energy due to clutch action.
4, Be very careful not to introduce dirt in the system through your filling technique [point of concern #1]
5. Dont over or under fill. [point of concern #2]
6. Use quality fluid [point of concern #3]

If 1/2/3 are done improperly, harm can be done.


Salim
ps: I am still perplexed as to why Lexus opted for autoTrans fluid instead to gear oil.

tempestv8

OK, I've found a discussion on Prius Chat from someone who shared their periodic fluid sample test results from their Prius on this thread:

https://priuschat.com/threads/transm...e.50971/page-5

See the PDF published by Jeff Deneberg. File can be downloaded from here without needing to be a member on that forum: https://priuschat.com/attachments/pr...ted-pdf.53677/
Most interesting re silica and viscosity particularly in the very first fluid change.

Makes sense to me to definitely change the fluid periodically and the most crucial period seems to be at the start.

And for those who want to know how to change the fluid of the front transaxle, I found a youtube video here:
Seems simple enough. Of course, great care needs to be taken to avoid introducing contaminants during the fill process.

Personally I would ensure that I could undo the fill plug first before draining the fluid, so I know I can refill the transmission.

tempestv8

Got around to doing the fluid change. The hardest part was removing the fill plug - there was just not enough room for my 10mm allen key. Eventually got it undone. The old fluid was surprisingly dark, given the short mileage (less than 47,000 kms) so I'm really glad its done.



As a comparison I undid the conventional auto on my 200 Series LandCruiser and the fluid was still a very clear red colour even after 100,000 kms since the last full flush.

I didn't get a chance to replace the ATF on the rear transaxle on the Lexus. That will have to be for another weekend.

I used genuine Toyota WS fluid, just to avoid any possible issues.

I am surprised that in the Nav system, there is an option to set a reminder for the ATF fluid change - if in fact Lexus don't recommend touching the transmission fluid, it's still nice that they give you an option to set a reminder for your fluid to be changed anyway in the vehicle's maintenance schedule.

tempestv8

OK, I've now found some concrete answers, after I ventured into the "Warranty and Service Book" specific for the RX450h.

According to Lexus, the ATF needs to be replaced at the 5 year, 75,000 km mark if the vehicle was used in "severe conditions", which are described as follows:

Operating in rough, muddy or snow melted roads.
Operating on dusty roads.
Towing a trailer, camper or using a car top carrier.
Repeated short trips less than 8 kms and outside temperature remains below freezing.
Extensive idling and or low speed driving for long distance.
Continuous high speed driving (80% or more of maximum vehicle speed) for over 2 hours.