Toyota Prius 2010-2015 Transmission drain and refill

Given the specialized materials used in the motor windings, and electrical insulation, I would also be reluctant to use anything not certified by Toyota as safe for this particular power split device.
I know that when I tested the Toyota fluid for its electrical properties, it turned out to be a true dielectric fluid with resistance higher than could be indexed by my ohmmeter at its most sensitive setting. I would worry that non-Toyota ATF might not have that dielectric quality and thus allow some degree of electrical leakage with unknowable but almost certainly adverse consequences.
I still would like to have a quick and easy method to check the fluid level in the PSD without jacking, leveling, and popping out the fill plug.

 

Regarding an easy way to check transaxle fluid level.

Why? As long as there are no visible leaks, where would the fluid go?

 

Fair question.
The PSD sits above the under cladding so that if you had an extremely slow leak from, say, an inadequately torqued drain plug, the fluid could collect on the cladding and evaporate without showing drips underneath the car.
Mr. Worst Case Scenario also suggests slow leaks into th CV joint assembly that would not be observable from underneath but detrimental to the CV joints, and the possible small hole or crack in the PSD caused by running over road debris (e.g. Top Of The World highway in northern Yukon) that would cause a rapid loss of fluid. Without a fluid check , the loss of ATF leads to transmission failure.
Just in my experience, I was able to avoid transmission failure in the cars we owned with ATF dipsticks, but had two transmission failures on cars that have lacked transmission dipsticks, due to slow leaks in both cases.

 

All the arguments listed against using ANY aftermarket fluid are valid and true.

Of coarse there is one other very logical fact that can't be disputed, the Toyota fluid has proven over time to do exactly what Toyota claims. The vast majority of Prius have never had their fluid changed with no transaxle problems.

The Toyota fluid has a proven track record and is cheaper. There is absolutely NO reason not to use it.

 

Drips may not show under the car, but if you drop the panel, you'll see definite accumlations, both on the underside of the transaxle body, and the top of the panel. Really hard to miss.

I've change the fluid a couple of times, and the transaxle's as clean as brand new. With every oil change you (or the mechanic) has a very good opportunity to look it over; any leaking and it'd be looking very grungy.

We've got a Civic Hybrid with a leaking oil seal where the drive shaft comes out of the CVT, very obvious, going to have them replace it soon.

 

It's one of mine too ! And I'm talking sense. Not brand loyalty.
There is nothing special about the house brand. It's just what they stock for their entire fleet.
It's just an ATF to profit off of.

AND.... If you follow "toyota's guidance on this" subject.... You would never change you ATF and let the transaxle grind itself to death on it's own doo doo, correct?

 

Bill, you don't even own a Prius. The Owners Manual warns against using anything BUT Toyota ATF-WS. I don't understand your motivation here.

 

Have you seen the inside of a transaxle? There isn't anything to "grind itself to death". It's not an automatic transmission. It does need an oil that resists conducting electricity.

I've talked to a Prius mechanic that has his own shop and performs maintenance on many prius used as taxis. He's only seen a couple of transaxle failures and it was due to electrical failure, not wear. He sent the fluid out to be checked and the fluid had lost it's resistance.

I changed the fluid in my 2004 with 180k on it and found almost no metal particles on the magnet. These transaxles last wether or not you change the fluid. People who get carried away with maintenance (which isn't a bad thing but many times isn't needed) frequent forums and tend to exaggerate. The amount of transaxle failures are very small given how many Prius are on the road and the vast majority of Prius never have the fluid changed.

However, if you want to change your transaxle fluid then using more expensive ATF in place of the recommended fluid (which has a proven track record) is just foolish. The Toyota fluid is proven in this application and every other fluid isn't. The thing that concerns me most is the electrical properties of the fluid. For that reason alone I'll stick with Toyota's fluid.

 

Greg,
Have you seen the oil analyses I posted in another thread on this very subject? There are at least 4, or more, oil analysis reports. ATF fluid changes ARE Required. | PriusChat
It is a simple box of gears and bearings. It needs a clean lube. There is not even on magnetic drain plug in the Gen3's.

All oil resists conducting electricity, yo. Why are the people NOT using the cheap house brand NOT reporting "electric problems"?
The house brand has a no pedigree, it is a, use it in all, all purpose ATF. It's nothing special.
But I understand Brand Loyalty runs deep....

And sorry, the old chain drive Gen2's and 180k miles and 'almost no particles'....really? Did you own if from new?
You'll have to show me. I'm from (KC) Missouri. Go ROYALS !!

 

FYI my MY2013 Gen3 Prius Lift-back II does have a magnetic drain plug from the factory.

 

I owned it since it had 43k on it and no I don't have to show you. You either take my word for it or not. I was surprise to see almost nothing on the magnet.

Glad the Royals won. I was hoping for the Cubs to win but the Royals were my second pick.

Go Patriots !!!!!!!! 19-0 this time!!!!!!!

 

My fluid in the 11 was clean when it came out at 100k recently --

 

Clean, but really dark?

 

Sorry, but if it was never change previously...I'm calling BS on that one.

 

At about 48429 miles, mine "came out" inky black (whatever that implies), but contained no ferrous particles large enough to find with a magnet or see in the bottom of the drain pan after I slowly poured off the fluid. It was the original WS, as far as I know.

 

Changed mine at 47k and observed dark, purplish color but no particles visually . Should have done an oil analysis but didn't.

 

There is no good reason to not use the approved transaxle fluid. The Prius transaxle doesn't have a reputation for high failure rates that would require using a different fluid to try and help the transaxle last longer. Using an unapproved fluid then selling the car to an unsuspecting buyer is antisocial behavior. Shame on you.

 

I won't personally use something other than WS, but I have yet to hear of any failures from using something else either.

 

This in particular is what bothers me: handing a cavalier experiment over to an unsuspecting buyer.

 

You probably never will hear of one because very few Prius ever have the fluid changed, there are very few transaxle failures and most people who do change the fluid use WS. Plus how is someone to know if it's WS fluid or something else in a failed transaxle if ownership has changed?