CVT vs ATF

In the manual it says to use "TOYOTA ATF WS", and that anything else could cause damage. I'm guessing that's what you used? If so you're fine.

Toyota does not recommend a transaxle fluid change, ever, which is a bit frustrating. A lot of owners replace it, quite early. There's no harm, and it's fairly cheap.

Dealership service departments seem to follow Toyota's recommendation for the most part, will call you nuts for considering a change, and are sources of a lot of misinformation on the subject.

From the North American Owner's Manual, page 563:



(Sometimes Toyota says "transaxle", other times "transmission", same thing.)

And excerpt from the Repair Manual, bare bones description of the fluid change:

 

I would change again with toyota fluid

 

I don't see anything on the bottle that says compatible with Toyota ATF WS. And even if there was, I wouldn't use it. This is just one case to stick with the proprietary fluid, no upside to doing otherwise.

Then there's me: I would change with the Toyota fluid, drive it a day, change it again, drive it a day, change it again.

That's the drill for a typical transmission that's had contamination, one that drains only 50~60%, so with the Prius transaxle draining about 90%, I'd be more-or-less comfortable with that. But kicking myself.

OTOH, there are a number of people here who can't resist trying an alternate fluid. Good on them I guess. That's one reason I've no interest in a used Prius though.

FWIW, I once started dumping motor oil in a Honda automatic. Got about 1/2 cup in before I woke up. Did the three changes drill right after.

 

The fluid has to withstand about 600V DC. That's why it's "special". It also has to not damage the electrical windings on the electric motor/generators and the insulation therein. It is also a coolant for those motor/generators.

Better get the correct fluid and change it.

 

+1.

I'm normally quite skeptical of using proprietary oils and potions, but the CVT in the Prius is a notable exception because if I'm not mistaken the Prius' CVT has stator windings (something a normal CVT does not deal with) which is the main reason that I'm an advocate of replacing the fluid every 30-60K despite the fact that the mother ship calls it a "lifetime" fluid.
I'm pretty sure that most non-OEM fluids would not cause electrical problems with the windings, but I'm not willing to bet a stator replacement on it, especially when the OEM fluid is available online, and the price difference is insignificant.

Some things I'm just not willing to roll the dice on.....

 

I don't think you'll notice anything. Well just peace of mind.

 

CVT = Constantly Variable Transmission The Prius transmission emulates one.

ATF = Automatic Transmission Fluid The Prius transmission uses Toyota's ATF WS.

A transaxle is just a transmission and differential in the same housing. Many Front Wheel Drive cars use a transaxle.

Toyota never mentions replacing this lubricant ever, which seems unlikely. As there is no official schedule, everyone has their own idea. I like 30,000 miles, then 90,000 miles then every 90,000 miles.

 

I felt that before the ATF fluid change in my eCVT , the starting of he ICE made a more noticeably hard "clunk" than it did after the change, when it again became more of a soft "thunk" as when it was new. I recall one other post that mentioned that same phenomenon. Might have been a level problem or viscosity degradation (the drained ATF at 45,000 miles was quite black), or just my imagination!

 

If you're going to use a product from that company, this one claims to meet Toyota's WS standard:


Edit: That said, Toyota ATF T-IV (which is, I believe, a variant of GM's Dexron III fluid) has been used in Prius applications before, though - the Gen 1 used it. That said, is MPM ATF HFM (or, for that matter, MPM ATF LV) actually non-conductive? I could easily see these aimed at some more generic specs, and working fine in T-IV and WS's conventional applications, but not the Prius.

I'd personally run genuine Toyota ATF WS in this application.

(It is worth nothing that the MPM ATF LV is also specified for Mercon LV, which likely says what it was originally designed to meet, though... and Mercon LV is what Ford recommends in their power split hybrid transaxles.)

Edit 2: Except Ford called for Mercon V in their earlier power split hybrids (before 2009) - which would be an application of MPM ATF HFM. In any case, I'd expect better fuel economy from using Toyota ATF WS (or probably ATF LV) - ATF WS was thinner than ATF T-IV.

 

well done, congrats! finally some positive feedback for fluid change.

 

That's actually not the right fluid either - ATF WS is the right fluid.

CVT fluid is for the true CVTs.

 

I will second the above. The correct fluid for the Prius is this

 

The 1st-gen takes ATF T-IV, the 2nd, 3rd, and 4th-gen take ATF WS. (Verified the 4th-gen myself per the owner's manual in the US.)

 

Third gen and fourth gen North American Owner's Manuals say to use "TOYOTA GENUINE ATF WS" fluid, and caution against using anything else. This is an excerpt from the 2016 manual:



That said, I've never seen description like the picture you've posted. I wonder if it's in fact the same fluid, or not.

I would recommend a change, with the correct fluid, quite early, say after one year of ownership, and/or around 10,000~15,000 kilometers. Subsequently changes can be around every 30,000~60,000 km interval, depending on your time and inclination. It's quite easy and cheap, especially for DIY.