IS 300h transmission fluid still OK after 270k km (170k mi)?

[chnapo]

Hello,

new owner of my first Lexus (IS 300h 2015). First I have to say that the car is awesome, people who never drove lexus are truly missing out.

So about the question: After reading many discussions I learned that the ATF is not to be replaced as per manufacturer specification it lasts the car´s lifetime. But most people discussing had around 100k miles driven on their cars. I just bought mine at 270k km / 170k mi. Runs like a charm, I have to admit that I am impressed with the state of the car, I would guess half the mileage. But I am planning/hoping to drive it beyond 400k km / 250k mi and I have my doubt about the ATF lasting another 8 years and 80k miles without damaging the transmission. Is there any owner of the same model (or one with the same transmission) who has high mileage and can kindly share their personal experience? Or a mechanic who had opportunity to work on such a high mileage transmission? Is it better to let it be or seek a service center that can replace the ATF?

Also, any other tips for improving/maintaining the eCVT reliability and longevity?

[wharfhouse]

1 hour ago, chnapo said:

Hello,

new owner of my first Lexus (IS 300h 2015). First I have to say that the car is awesome, people who never drove lexus are truly missing out.

So about the question: After reading many discussions I learned that the ATF is not to be replaced as per manufacturer specification it lasts the car´s lifetime. But most people discussing had around 100k miles driven on their cars. I just bought mine at 270k km / 170k mi. Runs like a charm, I have to admit that I am impressed with the state of the car, I would guess half the mileage. But I am planning/hoping to drive it beyond 400k km / 250k mi and I have my doubt about the ATF lasting another 8 years and 80k miles without damaging the transmission. Is there any owner of the same model (or one with the same transmission) who has high mileage and can kindly share their personal experience? Or a mechanic who had opportunity to work on such a high mileage transmission? Is it better to let it be or seek a service center that can replace the ATF?

Also, any other tips for improving/maintaining the eCVT reliability and longevity?

Always an interesting discussion. I have a 2014 IS 300h that has now done 143k miles on original transmission fluid. The ecvt is different to a traditional auto box (much simpler) and so the same criteria don't really apply. I know of at least one IS 300h in this forum that did over 230k miles on the original fluid with no issues along with other Lexus and Toyota hybrids with ecvt that have done the same or more. I haven't heard of any ecvt failures in this forum. There isn't anything that can be done to prolong the life of the ecvt other than making sure there are no leaks etc. Changing the fluid is relatively straightforward - more like doing a manual gearbox - but you might struggle to get a Lexus dealer to do it however as they will stick to the lifetime fill advice. Personally I don't plan on replacing my fluid - I'm keeping the car for the foreseeable future and cover about 15k miles per annum. For reference I had a BMW 538i in 1997 that had a lifetime fill auto box - I kept that car 10 years and did 210k miles in it on the original transmission fluid and it never missed a beat and ran as well as ever when I sold it and so I am inclined to believe Lexus / Toyota's view on lifetime fill more than YouTube videos seeking views. But each to their own choice. 

[Notamech]

I happen to be of a different school of thought vs the above i.e i had mine changed on my IS at around 90k miles and will be doing the same on my GS300h as well at its next service (~80k miles). If you plan to keep the car long in my opinion changing the fluid is unlikely to cause any problems. Plus you have the psychological satisfaction of knowing it was done. In theory no fluid can hold the same properties forever and the transmission oil will lose its properties over time so perhaps best to change it. Especially because you do it once in 5-8 years and its not very expensive.

However, as pointed out above there are cars including some prius taxis that have mega miles without the ecvt failing despite never changing the oil. This could be down to the design of the ecvt. My understanding is the primary function of the transmission oil in the ecvt is cooling rather than lubrication and hence maybe even if the oil is old and black it doesnt matter it will still conduct heat all the same. 

But since changing it was only around £130 or something at lexus Hayes, i got it done anyway for the satisfaction of knowing it was done.