Just bought a 2008 Sienna with 228k miles. Replaced dead alternator, front wheel bearings, inner tie rod, front rotors and pads. Runs and shifts great.
I've watched hundreds of Scotty's videos and still don't know, is it recommended to change ATF on high mileage Toyota transmissions? He says replace ATF regularly, unless it has very high mileage, but also says Toyota transmissions are solid.
So does this rule still apply? Will new fluid extend life or cause harm? Previous owner told me he has never replaced it. Thanks!
How does the fluid look?
Whatever you do, do NOT have a transmission flush done on the vehicle. That will likely kill the transmission, given how gunk is shoved around via high pressure.
I'm sure that the fluid is going to smell and look pretty bad.
You do have an option, though. A drain and fill only will replace the fluid in the pan, essentially (not directly accessing the fluid in the more vulnerable torque converter). This will allow fresh fluid to replenish the additives that will keep the various seals in the transmission more supple, which is something that is desirable.
A few points: 1. Use the recommended OEM fluid, only. (In this case, I believe it's WS-ATF, but you should confirm). Do not use any other fluid that the OEMs. (Scotty makes this point, frequently). A non-OEM fluid will mix poorly with the remaining OEM fluid, creating harmful chemical reactions in the transmission.
2. You can do this yourself, with some care. Measure what you've drained from a warm to hot transmission pan, and then pour the equivalent amount of WS-ATF into transmission (once you've tightened up the hex bolt to factory specs), slowly, via a funnel into the ATF dipstick tube. Let the engine run, after you've replenished the fluid, and check the fluid level, several times. You don't want too much fluid in the transmission. It's important to be precise.
There are a number of video tutorials how to do this (including Scotty's) on YouTube.
