Another ATF Thread :)

At the very least, do whatever the manual says. It has been my experience that all fluids in all cars should always be changed at intervals. No such thing as a truly lifetime fluid. Stuff wears out.

 

the manual calls it 'lifetime'. that's why the dealer won't do it, they get to replace your tranny down the road with no guilt. but you can find dealers who will do it.

if your looking for a reason, you'd have to search back to people who had the fluid lab tested.

 

I recall how the people who have tested the fluid in the transaxle after 30K miles or so have seen that it is full of crud. But are there reports of anyone actually having to replace the transaxle due to wear caused by the dirty fluid? After all, the Prius transaxle is an utterly trivial mechanical device compared to a conventional automatic transmission (no clutches or belts); all of the complexity is in the control software.

 

My dealer said they never change it before 100,000 miles unless there is a problem. That doesn't sound too good and it shows every dealer has a different story. I'm keeping my finger crossed and wait until then I guess.

 

it would take some serious testing to prove that contaminated oil caused premature wear. i'm sure toyota has done this, and is comfortable that they won't have to replace many tranny's on their dime.

as far as user testing, it's simply a matter of blackstone report showing higher than 'normal' metals in the fluid. it's a precautionary tale, but not a proven one.

 

Sometimes manufacturers claim a lifetime service interval on fluids to give the appearance of their products being less maintenance intensive. BMW did this back in the late 90s/early 2000s with their transmission and differential service intervals. They claimed "lifetime" fluid and put "lifetime" stickers on the transmission and differential cases. These same exact transmissions and differentials including the fluid were just 60,000 mile items the year before. This change was implemented as part of a marketing campaign to drive more people into BMW dealers in order to challenge the perception that BMWs were maintenance intensive. There are many BMW automatics that go 200k and beyond on the original fluid but if it were me, I'd change it well before.

In the case of the Prius, you're probably fine using it for a lifetime. It doesn't cost much to change though and I'd just do it.

 

I thought I'd check that out, search my pdf of the (North American) Owners Manual and the (US) Warranty and Maintenance Guide.

In the Owners Manual, the word "lifetime" doesn't appear. There are various instances of "transmission", none of "transaxle", and the most relevant info is on page 563, as follows:



All I can take away from this is that fluid transmission may be needed, here's what and how much to use. But no hints as to when and why.

In the Warranty and Maintenance Guide, "transmission fluid inspection" is mentioned at various service intervals, and "transaxle" rears it's head in the warranty description. Replacement is never mentioned.

So yeah, while there's no declaration that the fluid is "lifetime", it's inferred. But they never stick their neck out, make a positive stand on the subject.

Anyway, I think the first change is the most important. I kinda shudder when I hear owners say things like "I've got 90,000 miles, think it's time to change it?".

I did a first (DIY) change at the one year mark (a little too embarrassed to disclose how low the mileage was) and it was quite dark already. I let a couple of years transpire before doing a second change, and was pleasantly surprised to see near-new looking fluid coming out. From here on I think I'll do it every third years, at the most.

With our dealership, I've never had a problem getting the fluid at the dealership parts department. Not sure what reaction I'd get dealing with service department tho.

To Markabele: if you can do it yourself, that might be the simplest route. If that's not in the cards I'd try talking to another dealership, might be an eye opener. You could print this out and bring it along, an excerpt from the Repair Manual:

 

It's not lifetime, at least if you want the PSD to last as long as the rest of the car. The FSM has a long'ish time period before the first drain/refill (~100k IIRC), and then a shorter period for each of the following drains/refills (~60k). People who have done oil analysis suggest the opposite. A quick drain/refill to get the particles from the manufacturing process out early, and the following drain/refills can be done at a longer interval since most of the crud comes out during the first drain/refill. Any time based refill requirements should probably be adhered to though, since the electrical resistance of the fluid may degrade with time and mileage.

 

^ I agree completely, with the gist of it. But I'm completely asea, regarding PSD and FSM, can you spell them out?

 

Power split device and factory service manual.

 

Something else to consider, the PiP has a larger electric motor that runs at higher speeds before the ICE kicks in. That probably puts additional stress on the transaxle components compared to the regular Prius hatchback.

 

The Prius Repair Manual (aka Factory Service Manual) gives no guidance regarding when (or if) to change the transaxle fluid. From my experience, and early first change and then a longer interval is good. Say first change at the the one year mark, then every three years thereafter? With normal usage.

(Take a look at my Repair Manual excerpt in previous posting, that's all they say on the subject.)

 

You've nailed it right there. I wonder who still charge cycles their cell phone to fix the memory effect even though most cell phones are lithium. Can you imagine telling an IT guy of the 90's that defragmenting a hard drive of the future will actually decrease the lifetime of the drive instead of making it go faster? SSD's never need to be defragmented. Degauss the monitor anyone? How about typing "www" in front of a web address?

I'll embrace the present and change my oil at 10k miles per owners manual. I'll ignore the color. Others can do their 500, then 1000, then 5000 as they've always done. The ATF will get changed per owners manual which is never.

You can tell I'm an IT geek that knows nothing about cars. So take what I say with a grain of salt. I plan to keep my car a long time and I will follow the owners manual. That is unless I get conclusive proof otherwise.

 

There have been a few transaxle failures in Gen 2 Prius vehicles. Most had advanced mileage (+150k). Whether changing the transaxle fluid will get you more trouble free miles? Who knows.

 

For $40~ and a couple hours interesting work, I'll hedge my bets.

 

Same here.

 

LOL...if there is a 'problem' then it is already too late! What a dumb excuse from your dealer.

 

i expect what's been posted so far is about as helpful as all the other atf threads.

 

You mean about as helpful as a debate about politics/religion..right?