Should I change the transmission fluid at 25K/3 years of ownership, or not?

All,

I just read all 6 pages of this "debate" and can see both sides. However one thing nobody is talking about is the year or Gen of the car. Is there a difference in the Gen 2 and Gen 3 cars in this regards? It appears that most people who changed their Gen 2 said the fluid was dark ect. However, most Gen 3 owners on here said when they changed it, the fluid was still newer looking. Could there be a difference here or are both basically the same thing and should not have change on the different generations? I know they (Trans) perform the same function, but there must be something accounting for the observed fluid differences...........

 

The Gen3 PSD replaces a chain with an extra gear in the drive path. This would not account for a difference in the appearance of the ATF at 60k miles. Toyota may have started to do a better job of polishing the gear teeth which would minimize the break-in accumulation of metallic particles in the first ATF drain, but I have not seen any evidence of that. I am still waiting to see a set of Lab analyses on Gen3 Prii ATF to see if any changes in the our ATF study group suggested drain/refill schedule is justified. For now the schedule we suggest is:

• Gen1 (2001-2003) - Type IV ATF - First refill at 15k miles, then every 30k miles thereafter
• Gen2 (2004-2009) - Type WS ATF - First refill at 30k miles, Then every 60k thereafter
• Gen3 and later - Type WS ATF - same as Gen2 until more evidence justifies a different schedule

It is, of course, your car and the decision of what maintenance strategy to use is up to you.

JeffD

 

I changed my transaxle fluid at 25k miles and it was a very dark burgundy color and there was a fair amount of metal on the drain plug magnet. I have the Gen III. So the Gen III fluid gets as dark as the Gen II.

The new Wth-AS is a bright pink color.

 

I changed mine around the one year mark, at 15,000 km's, darker than the new stuff. I'll likely leave it a couple of years from now on. I don't recollect that the drain plug was magnetic. Might have been, I'm a little fuzzy on it, but I think not. Maybe depends on your country?

Hey, I think it's WS-ATF. Likely short for World Standard - Automatic Transmission Fluid.

 

I don't know, I kinda like Wth fluid.

 

Thanks for correcting me . That is what I get for typing so fast and not proof reading before posting!

 

And I thought it just might be revealing how you truly felt about that stuff.

 

What is not to like about "World Standard" transmission fluid ?

 

It's great when it is "World Standard" -- not so great if it is "Wth" Standard.

 

FWIW, I had an overfill in my other car (a Camry Hybrid) a couple of months back at the dealer. The MPG went down about 8% right after an oil change and when I checked, the oil dipstick showed overfilling. WHen I took it in, they said it was overfilled by a "quart-of-a-quart". The Service Writer (at checkin time) seemed to want to replace the whole oil, but I mentioned I had Mobil 1 0w-20 in there. In the end, they just drained the extra (thru the drain plug end and retightened it), which came to a "quart-of-a-quart". No froth I could see on the oil dipstick, so I hope my car ended up being ok.

I am still debating whether I would trust them enough to touch the transmission, even if I decided to get a Transmission drain/refill done.

 

As long as they have the car on a (horizontal) lift, it's pretty hard to screw up a transaxle fluid fill, well, at least the level. The maximum spec'd fill is "level with fill hole lip", and that's pretty much idiot proof. unless they just keep slamming the bottles in there and smack the fill plug back on real quick.

The biggest issue, at least with some dealerships, is apparently getting them to do it, since it's not on the schedule. Funny, considering the multitude of other non-schedule services many dealers push.

 

Again, there is no evidence here or anywhere else that changing the TA fluid sooner than recommended interval is of ANY benefit.

 

I can't speak about the anywhere else aspect, but for the "here" part I'd agree. Still when I ask for advice from a doctor or a lawyer, I don't expect it is something anyone has access to without training and experience. When I ask a mechanic and get the advice I received, it was worth the $100 to me to proceed with the change in transaxle fluid. It also has me rethinking my switch from 5,000 to 10,000-mile intervals between oil changes (or at least between filter changes).

You won't find me telling everyone this is a "must do" event, but you will read my experience and the decision I made based on my reading, discussion and consideration.

 

Back a few years when I used to monitor Yahoo group PTS (Prius Technical Stuff) I believe that the UOA of WS-ATF in a Gen 2 Prius showed that it was out of viscosity grade at 60K miles. I believe that is at least part of the reason that some owners have picked a shorter change interval. I just changed mine for the third time (10k, 40k and now 70k miles). The parts guy at the dealer thought that I was changing it early ("Its a 100k fluid" - possibly, but in which vehicle and under what conditions?) I had a 6 word reply for him - "How much is a new transaxle?"

 

Sorry for reviving this, but I find this thread hilarious. The vigorous fight for and against, that is. The irony is most people "agree" that factory engine oil has to be replaced as early as after 1000 miles to remove "production debris" and "casting sand" yet they allow ATF for a lifetime.

The irony is great as early engine oil changes have no measurable benefits as there is a full flow oil filter and early oil changes promote more wear (new oil has inactive AW additives).

Yet, ATF has no filter in Prius, and there is a potential of early changes making things better in terms of transaxle wear. After all, the fact that particles in oil promote wear is well documented in the literature.

Full disclosure: I kept factory engine oil for full 10,000 miles and plan to replace WS ATF at the 25,000-30,000 mile mark. Sounds like easy DIY.

 

Ugh, i can't believe i just read through seven pages of bickering... I personally did change the transmission oil at 30k miles and do plan to do it at 60k mile interval. personal choice and piece of mind for a car i plan to keep for a long time.

This is kind of irrelevant but funny, but pertaining to "evidence that there's ANY benefit to changing fluids" i have a short story. My last commuter car was a 98 park avenue with the supercharged 3800. It had 124k miles on it and body was in rough condition. I did one oil change on it when i first bought it, after that i discovered it leaked about a quart every 5k miles. It was a car i got cheap and wasn't real concerned about. I ended up just topping it off with supertech 10w30 non synthetic every so often, for the next 100k miles. Yes, no real oil or filter change in 100k miles. These were all highway miles put on in about 3 years. I gave the car to a family member at 230k miles and is currently around 270k miles. i believe he started the oil changes back up.

So, one could say you don't need to change the engine oil... just add a little new to it... But i have no supporting evidence to say it will or will not extend your engine life

 

oh, and it was the original transmission fluid as well, was topped off once in my posession

 

For the folks who read all this and decide to do the ATF change here is a good pic of my Prius gen III 2011 drain/fill plugs.