I have a 2018 Toyota Rav 4. about 55k miles. I was going to change the transmission fluid myself with the Toyota WS fluid, but I do not have the time. I spoke to a mechanic and they said that they recommend doing it twice to get more of the old fluid out. I have been under the impression that leaving some of the fluid behind was desirable. can you discuss / recommend what is best for a Toyota?
I have been under the impression that leaving some of the fluid behind was desirable
There's no benefit in keeping dirty fluid inside a normally operating transmission.
can you discuss / recommend what is best for a Toyota?
When you drain the 6 speed transmission a lot of the fluid remains suspended in the torque converter. Upon refilling and driving the car all that fluid gets mixed together. The 2nd drain and fill allows further dilution of the old fluid with fresh fluid. That old fluid which was suspended in the torque converter has now been replace with 2 even fresher mixes of fluid. Although it is not absolutely necessary to do multiple drain and fills, it is good practice. Many mechanics will even do 3 or 4 drain and fills to introduce as much fresh fluid as possible.
The frequency of change is dependent on your type of driving but every 60K miles is a safe bet. ( I do mainly stop and go city driving so every 45K miles for me)
I have been under the impression that leaving some of the fluid behind was desirable
Nope. There's nothing beneficial in the old fluid to your healthy transmission.
Maybe you're thinking of a flat worn out transmissions with no clutches left, and the gritty fluid is the only thing keeping it going.
they recommend doing it twice to get more of the old fluid out
it's not necessary as long as you change it regularly.
about 55k miles.
perfect. Do it now, and then do it again at 100k. Less, if you tow or haul.
See our FAQ for more info.
You could also do a full fluid exchange. Not sure your specific vehicle, but it can usually be done by pulling the transmission lines to the radiator, draining out one into a bucket, while new fluid goes in the other. It pretty much drains everything.
A good mechanic will know how to do it properly.
great way to create new problems.
@imperator Yeah it looks like the car care nut agrees. I thought the non pressure fluid exchange was the way to go, I stand corrected. Not to mention multiple drain and fills.
If you know your transmission guy and absolutely trust him to do the right thing, then sure. But I wouldn't recommend it to the general public. Especially, if they're going to a chain or quick lube place. It could quickly turn into a very expensive mistake. I think we've had more than one such case here on the forum where the line blew off or something similar.
https://carkiller.com/scottykilmer/qa/coolant-leak-after-automatic-transmission-service/
Plus I think the benefits of changing every last drop are marginal at best. It's a diminishing return. I think it's more economical for people to just change it a little more often.
perfect example: Tech "forgot" to re-connect transmission cooler lines after performing a flush. Owner did not make it home before transmission was destroyed.
https://www.bitchute.com/video/67qr9FgqcftO/
@imperator Yeah for sure you don't want just anybody doing it.