Anybody over a 100k miles and still on the original transmission fluid?

lots of people. there is no dipstick, and you don't need to check.

there is a drain plug, and a fill plug. pull the fill plug first, the oil should be at the bottom of the hole.
then pull the drain plug. when it is done draining, replace the drain plug with new crush washer, fill to overflowing, and replace the fill plug with new crush washer when the overflowing stops.

 

it can, but i cant give you odds. we see very few tranny problems here, in very old prius.

oil change is easy, should be a hundred bucks, parts and labor

 

no, most do it themselves. the big thing is a lift, it has to be level. easy for your mech, even if you have to show him a youtube video.

worth calling a few dealers though. every now and then, a service will be a reasonable price.

 

toyota claims the ATF is "lifetime".

I'm at 101000 and I've changed the fluid twice, simply because I do it myself.

 

hey, when your tranny blows, that is the lifetime

 

A few more tips:

Toyota cautions to not use anything but “Genuine Toyota ATF WS” (in Owners Manual), from freshly opened bottles (in a TSB), and says anything else may damage the transaxle (in Owners Manual).

When refilling, fill till it starts coming back out, with the car level.

It’s a good idea to remove fill bolt first, just in case they’re hard to break loose.

A funnel with approx 3’ tube extension from above is an easy/simple fill method.

Not sure of Prius c fill/drain torque spec, but fwiw 3rd gen Prius is 29 ft/lb (for both, from Repair Manual).

 

I always change the ATF immediately when we get a used Prius.

I just did the job on the Prius c we picked up a few weeks ago...and while the fluid wasn't really nasty like it was when I changed the ATF in the Prius v wagon...it certainly didn't look great either. Makes sense though as the Prius c only had 65K or so and the Prius v had 128K on the odometer when the ATF was changed.

Point is...the more miles on it, the more I'd prioritize changing it out! And yeah...stick with the Toyota ATF-WS stuff. Absolutely no point to use an off brand for something that is changed so infrequently.

EDIT : Forgot to add the bit about car leveling...perhaps the most tricky aspect of the job. Crucial to get a proper fill. Here is a post with a couple pics of how I did it :

• Hi all, new Prius C owner | PriusChat

 

Correct!

^this.

Take Care to ONLY use Genuine Toyota ATF WS” from freshly opened bottles.
Normally I almost never say this, but the "transmission" in the Prius has electrical components that can be very easily damaged by non-OEM (factory) fluid or even OEM fluid that has been contaminated with foreign material.
That's why they strongly recommend using sealed containers.

The procedure is very simple, and any competent and trustworthy mechanic can do it for less than $200.

My company uses Priuses as fleet vehicles and they never change the fluid, and almost all of our cars have WELL over 100,000 miles on them. The Prius transmission/transaxles (they are actually called power split devices) are sealed and there is no combustion or traditional wear components, and the operating temps are relatively lower than traditional transmissions or transaxles.....BUT....

It's still considered to be a 'best practice' by many on this forum to replace the fluid if you buy the car used or if you intend to keep it for more than....say about 50,000 miles.

JUST REMEMBER that while this procedure is very simple and relatively inexpensive, like many things, doing it incorrectly can be much much worse than not doing it at all!

Good Luck!

 

$100 USD (max) would be fair. I’m pretty sure @Tideland Prius saw a Canadian dealership service department promotional deal (whew!) of $79.99 (CDN) for this. It’s on par with an oil change.

Even a somewhat addled and slow-as-molasses DIY’r (me) can pull it off, with floor jack and safety stands. For the dealerships, with full lifts, it’s trivial.

 

Almost 110,000 miles, still original transaxle fluid, i still need to figure out a way to lift the car on its 4 wheels and have it in a leveled ground, also need some kind of pump to get the fluid up there. But i don't think it is that important to change the fluid on the Prius transaxle, there are taxi Prius that have made it to 300,000 miles with original transaxle and original transaxle fluid. The primary function of it is to lubricate, and then cool, and even if it's dark, it is still doing what is supposed to do, there is a magnet that collects the metal shavings so the electric motors won't be at risk of getting damaged. My electric motors do not get past 100° C so the fluid is doing what is supposed to do, cool them down and lubricate, i will still try to change it as soon as i can.

 

IIRC you replaced your brake accumulator, or pump? Something significant… just saying, your DIY abilities are pretty dang advanced, a 4 point lift should be a cakewalk. My drill, fwiw:

1. With parking brake off, chock rear wheels fore an’ aft.
2. Raise front with floor jack, at front/centre jack point, and settle onto jack stands*.
3. Raise rear with floor jack, at rear/centre jack point, and settle onto jack stands*. Aim for roughly same amount of raise, verify with level on underside of rocker panel seam, but don’t go nuts.
4. Bring it back down to ground in reverse order.

I do the above raise at least twice yearly, when swapping between regular regular and snow tires; it’s very straightforward and becomes second nature.

An alternate method a lot here use: run front up on ramps, raise rear with floor jack, preferably then settled onto jack stands.

About the “pump”: you really don’t HAVE to use one, a funnel and tube extension from above is dead simple and works fine. Use them only for Toyota ATF WS, if you’re obsessive.

* Either at scissor jack Toyota proscribed bearing points, or more substantial and stable alternatives. On my gen 3 I place front jack stand cradles at leading end of the main underbody longitudinal “rails”, and rears at the heavy plate humps just ahead of the oblong shipping pin holes.

 

Thank you very much for providing easy steps on how to do such procedure, i might try it in the next few weeks. I just feel like even putting a little bit more of fluid, or a little bit less, is going to cause a catastrophic failure in the transaxle, or if even a small amount of dirt gets in, or water, the area needs to be cleaned very well before proceeding to open the fill nut and bleed nut, same goes for the extension and funnel.

And yes i had to replace the brake pump assembly and brake booster assembly by myself on my 2012 Prius C, sadly. But saved a lot of money.

 

Some things to consider are that the Prius C transaxles are oil cooled via the housing so the oil has been proven to get dark much faster then other Prius models. As far as 300k original oil. I have never seen it. I don't doubt it though but a Prius C oil would have broken down more then the other models due to the hotter running air cooled transaxle. I have no doubt though that a 300k mile transaxle with factory filled oil never changed Vs. 300K transaxle with a drain and fill every 30k miles will have far less wear if dissembled and inspected. The other issue is noise. I would suspect the transaxle with 300k factory fill will be noisier due to more bearing wear.

 

I do not think that you can overfill a transaxle, based on what I have read.

Like many “experts” I have not replaced the fluid myself but my understanding is that the transaxle is filled until the fluid level is just below the bolt hole on top of the unit.
Since you have to put the bolt back in to finish the procedure, it would be hard to get in more fluid into the transaxle.
I’m thinking that since there’s no dipstick in the transaxle, it would also be pretty hard to under-fill the unit as well.
Most Priuses operate right-side-up, so the fill level should not be an issue.
Making sure that you have the right fluid…..and that no contaminants (grit, dirt) get into the the fluid, and making sure that you remove the top bolt first, and replacing the fluid with the car mostly level seem to be the important steps.

As mentioned above….pretty much just like a oil change in simplicity.

Good Luck!

 

The fill hole is towards the back IIRC, so using both my brain cells I think if just the front is raised you’ll overflow a little sooner. OTOH not by much, and the spec is “at the lip, plus zero (naturally) to 10 mm lower”, IIRC again.

 

Interesting bit about the Prius C - P510 transaxle cooling! Since we now have a Prius C in the stable, I was observing the MG1/MG2 temps on a highway drive over the weekend ( FYI - I use the Engine Link app ). Sure enough, MG2 seemed hotter than on our Gen3 based vehicles.

When I got back I was curious and dug up the Weber Auto video on the P510 here :

He mentions the that "the fluid when I opened this one up was really dark...and stinky..like hot stinky...or it could be an indication that these tranaxles run hot" ( see 9:54 in the video ). However, it was more of an observation...not necessarily a critique. But the fact he bothered to address it is telling.

He also describes the "cooling tube" at 12:50 in the video. Basically, there is a small tube that pumps fluid onto the top of the stator...and that is what 'cools' it. Personally, I was wondering if old, thicker fluid might take more work to pump and therefore have less cooling capability? Something to think about....

He also looks at the external cooling delivery pipe ( 16:50 in the video ). Since this is a external pipe, it sure seems tailor made for DIY'ers too install a small cooler!

It sure seems like the takeaway here is to the change the ATF more frequently in the Prius C.

Also interesting that the Prius c has the Gen4-like stators ( see discussion at 5:20 in the video ). Pretty cool combination of "old and reliable" ( the older model engine ), and new ( Gen4-like stators, larger oil pump for cooling purposes etc... ).

 

Indeed, the stators in the Prius C i would say are far more reliable and less prone to have some kind of short circuit than the old design. My Prius C MG1 and MG2 temperature never go beyond 100°C as far as i have been monitoring them.