High Mileage Tranny Fluid change

Just change it

 

Good News! You do not have a transmission in this sense. It has no torque converter or clutch, so nothing can ever slip. It never shifts gears, so it cannot fail to shift.

A normal automatic transmission uses hydraulic logic circuits to decide when to shift, they have twisty little passage, that can be clogged. (see below) The Prius does not have any equivalent, as it never shifts and uses electronic logic not hydraulic.

Your Prius is free of these fine passages in the transaxle.

 

Yeah change it. Just for a counterpoint: I've changed ours 3 times now, and I'm at 67K kilometers, lol. Even I'll acknowledge that's overkill, better pack it in for a while.

Get four quarts (or liters) of Toyota ATF WS, and the fill and drain bolt washers (I believe they're different sizes on 2nd gen?). Dealership parts department is safest bet. Simplest way to put the new fluid is with a funnel from above, with a tube extension. Fill with the car level, till it starts coming back out.

 

In some senses, a Prius does have a transmission. Also Transmission means different things in British English than in American English.
In British, the transmission is what I as an American, I think of as the drive train. In American, the transmission is the part that provides different gear ratios.
Transmission (mechanics) - Wikipedia
One train of thought is that the Prius has a very talented differential. There is only one ratio, and there is no clutch, so no gears change.
In the philosophical, however, it accomplishes the functions of a transmission, "the transmission adapts the output of the internal combustion engine to the drive wheels."

The Wikipedia article waffles: "The canonical example of the EVT is Toyota's Hybrid Synergy Drive. This implementation has no conventional transmission, and the sun gear always receives 28% of the torque from the engine.

My point was that of all the reasons folks make up to avoid changing their ATF, none actually apply to a Prius. It is never a bad Idea, and I do so at 30,000 miles, 90,000 miles, and then every 90,000 miles.

 

When I first saw some essays and videos on the Prius "transaxle" I actually felt a bit "short changed". After a bit I came to understand: it is very simple, and effective.

 

The fluid is doing to be VERY dark. Why not just change it? So easy.. and only $40. It once in the cars life time.. worth it.

 

What size tubing is needed to fit the fill hole properly? I’m getting ready to do this.

 

The only concern is that the tubing not be too big, that it can't fit the hole. I believe the stuff I'm using is slightly under 16 mm OD (5/8"), and that still had a bit of room. If you're using funnel from above, you'll likely end up with funnel plus about three foot hose extension. So maybe buy four feet, so you've got leeway, for fine-tuning.

Addendum: went out and actually measured, it's around 15 mm OD. Again, that had a little play still.

 

Thank you very much!!!!

 

Only caveat I have is the fill hole bolt is really socked on there if your the first to remove it. It may have thread lock on it from the factory.
Use a breaker bar and longer the better. I have a one inch emit pipe cut into various lengths for custom breaker bar. Just slip it over the ratchet.

And make sure your going the right direction you can get turned around under there. Don't want to be wailing on a bolt and your actually tightening it.

 

Things went well, it is surprising how easy it was to do the swap at my buddy's place since he had jack stands and a really nice jack. It drained out super dark, but at the end it became lighter. Refilling, it took right about 3.75-3.8 quarts and then started to spill out of the fill hole. The car is noticeably smoother now. Thank you all again for your help.

Also, a huge plus was finding that my front shock are ROCKED before there becomes a major issue. The boots are done and they are starting to leak oil. So guess what is up next!

 

You run the risk of breaking your ratchet wrench though. If it's cheap tools and you don't care, and it has to be done, well there you go. But best bet would be to buy a decent quality longer handled wrench; it will be beefed up, designed to to take the greater torque of the long handle.

 

I agree. But most people may not have a breaker bar. I have done it myself a few times as was tired of rolling out from under the car to get it. A Craftsman will take it a Harbor Freight will not.

 

In my early 20s, my car was a 1962 Ford Falcon, my wallet was continually empty and my tool collection was what I found, begged or borrowed -- mostly cheap, but my dad did grudgingly pack me off with a few of his Proto tools -- which in the day were top-quality and I still have and use them.

However, I needed a breaker bar and K-Mart of the 1980s was my go-to place for tools.

In my first few uses the actual knuckle snapped off (the black part below)



At the time, K-Mart had a "lifetime warranty" on their auto tools, so back it went. The woman at the service desk insisted that the knuckle was supposed to come off like that and kept trying to jam it back onto the bar and convince me to go away. Finally had to insist on a manager. They would not refund, but did replace. The second bar actually lasted some 20 or so years.

 

Bumping this thread.
I’ve read many on the issue (arguing whether or not to do the change, what fluid to use, etc.)
I’ve come to the conclusion that if I do this, I’ll stick with the ATF-WS.

Here’s my sitch: I recently got a 2005 with about 340,000 miles. I can’t be exactly sure, as the ODO only reads to 299,999. I use the trip to track oil changes / adding oil.
As far as I can tell (per the official Toyota service records) the Transaxle / Tranny fluid was only changed at the mandatory 60,000 mile maintenance. That means my baby has 280,000(!!) miles on the current fluid.

Should I risk doing this? Is there any risk? From what I’ve read there is no inherent danger, but for some reason I’m still wary of it.

Thanks in advance!

 

No risk, aside from bruised knukles.

 

Haha I’m sure that’ll happen

So it’s generally a good idea?