i replied to a post on the non-hybrid section about tranny fluid and thought a question i had might be better suited here: Valvoline makes a tranny fluid for all toyotas (T-1V or WS) except--and they spell this out--except for hybrid model.It got me thinking(ouch!) what does the WS do for the hybrids?Are they all CVT's? Do the belts and cones in a CVT tranny need special additives?

There is no belt. The hybrid transmission is just a differential with a gas engine on one side and an electric motor on the other. Spinning the electric motor at different speeds varies the ratios.

https://auto.howstuffworks.com/hybrid-car7.htm

WOW!! I'm as dumb as a stump when it comes to transmissions but that article was eye-opening and very informative. Thankyou very much.

ATF within that "transmission", or Power Split Device, is for lubrication purpose only. It bears no hydraulic function similar to that in normal automatic transmission.
Both motor generators are cooled down by inverter coolant.

little guy on my right shoulder is saying to be quiet , while guy on my left is saying 'do it, do it!!'
....so i'll ask.Does it really matter then, if you use WS in the tranny?They say to use it but it's not a regular tranny ,right?

Little guy on my left shoulder is my Guardian Angel. I am nice to it, it's nice back to me. Thank you, GA.
That said, as it is not a hydraulic fluid, I always suggest only one thing: DAYOR. Do at your own risk. OF COURSE Toyota wants you to buy nothing but WS fluid. OF COURSE they will tell you that it is a must, as it is specifically designed for Toyota this and that and what not. It's called "good business practice".
Then there is common sense. Again, DAYOR. Whatever you feel comfortable with. Your car. Your decision.

Btw, T will say that it's lifetime fluid. That's another common sense decision. Mine tells me to change it every 50 000 miles. Thank you, GA.

ukrkoz: i didn't want this to turn into another fluid thread but i couldn't help but ask.As i said i'm not very tranny savvy but i think i agree with you ; this doesn't seem like a case for hydraulic fluid or at least WS.