Transaxle Oil Analysis

So, what is your explanation for a used oil analysis of the WS ATF at 5,000 miles that says the oil failed specification?

It does not. But that does not mean ATF fluid lasts forever. Once the car is past the warranty, why would Toyota issue any maintenance requirements that would extend the life of the vehicle? Some of us plan on using the car past the warranty and some of us plan on using the car beyond the last mileage intervals covered in the manual. In that case, changing the ATF fluid is very, very smart. Some readers of these posts have picked up on that. They have the ATF fluid changed to extend the life of the Transaxle. I did.

You should ask them to show you the leak at least before authorizing repair. Good luck!

No, having the seal wear out at 60K miles is not "normal". However it does happen, and Luscious Garage has reported this as well.

Since the transaxle is covered under the 5 year / 60K mile warranty, your car is probably just past that coverage. You might inquire whether they can give you a break on the repair.

Also, it would be good for you to get under the car and look at the half shaft where it comes out of the driver's side of the transaxle, so that you can see for yourself how bad the leak is. Good luck.

With that logic, Toyota doesn't have to put the "change spark plugs" in the service intervals...

The Toyota scheduled maintenance guide is not a "Bible". It represents the minimum needed maintenance so that the car probably won't have a warranty-related failure during the first 100K miles.

If 100K miles of service is good enough for you, then no worries. If you'd like your car to last longer than that, then it might be a good idea to consider additional preventive maintenance.

My dad's 2004 prius has 150k ish miles on it. still gets 56 mpg. Never did any transmission fluid service or anything like that. Our CVT transmissions are not like traditional automatics. And even traditional automatics have gone on for awhile on factory fluid.

My dad's 12 year old Mazda Miata with maybe 200k miles on it, 6MT, but still never changed manual transmission fluid. Only changed the clutch. Still shifts fine.

And i've heard the "preventative maintenance" story from people at jiffy lube before, recommending engine flush, coolant flush, everything flush. And we all know how those turn out...

Not saying transmission service is a bad idea, i mean it wont do any harm. But is it really necessary? well thats a different story. I mean if toyota suggested we do it every 30k miles, imagine how much more money they'd make... but they haven't.

Has Toyota said this ?

My personal take on maintenance over and above Toyota recommended is that the Toyota Prius engineering is genius but not infallible. As experience mounts and points to weak spots we would be fools not to adapt, particularly if the exercise is inexpensive and protects a costly sub-system. Put another way -- I hedge my bet of not buying an extended warranty or selling the car prematurely by early replacement of the inverter coolant pump and periodic transaxle fluid replacement. I like gambling when I have excellent house information available

"Necessary" is a relative concept (like "need") and my idea of necessary is obviously different than yours, which is fine. Reasonable people can disagree in good faith about this topic.

I'm in the small subset of Prius owners who have had used transaxle fluid tested. The amount of Si and Fe particles that have accumulated after 30K miles, as well as the decline in viscosity after that period of use, has motivated me to change the transaxle fluid at 30K mile intervals. It is simple and inexpensive to do.

If you consider it to be a badge of honor to have original transaxle fluid circulating at 150K miles, then more power to you.

No, I said it, with the implicit assumption that the maintenance schedule is the result of negotiations between the engineering and marketing departments. Evidence of that is the maintenance schedule for the same car differs by country. Although part of that difference may be attributable to differing operating conditions, at least some of that seems due to cultural norms.

For example, the JDM 2G Prius schedule allowed use of 0W-20 oil while in the US 5W-30 oil was prescribed. (This might be partly due to more extreme climate conditions in parts of the US.)

2G engine oil change is required at 5K mile intervals, while most other parts of the world have longer service intervals. (Probably due to the engine oil sludge lawsuit in the US.)

I understand that the European schedule includes periodic brake fluid changes while the US schedule is silent on that subject. OTOH, the US schedule includes periodic tire rotations while I understand the European schedule is silent on that subject. I can't think of operating conditions that would justify the differing recommendations.

Thanks for the clarification Patrick. I have no doubt that eventual service recommendations are flavored by more than just simple engineering, but I have always thought that most of the Japanese auto companies diverged from their US counterparts a couple decades ago in deciding to engineer for longevity rather than planned obsolescence. They realized that market growth had a lot more profit potential than churn from a stable customer base. Detroit has been in decline ever since.

But back to maintenance: Toyota's reputation is built on solid reliability for 200k miles, and up to 500k miles in a exceptionally maintained car. Honda the same. A maintenance schedule that lead to problems after 100k miles would destroy their hard earned reputation. So I think that if Toyota was remiss in not recommending more frequent transaxele oil changes, the recommendation will change or Toyota will improve the spec.

I believe that Prius gearboxes are good for 200k plus miles with no maintenance, but some of use can't stand to see a nice piece of machinery being worn out sooner than it should be because of contaminated oil. Even if that sooner than should be is over 200k miles.

I will change my transmission fluid by 10k miles and at some TBD interval of 30k-60k miles after that even though I fully expect to have the car less than 100k miles. The person who buys my car will get well maintained car.

If your position is to only do minimum recommended maintenance, I agree that your position is just as valid as mine. More valid than mine if your primary unit of measure is the dollar.:rockon:

Even though that last sentence sounds snarky, please don't take it that way. It's an acknowledgment that different people have different criteria and a car is just a piece of machinery.

My position is to use Toyota's reccs as a baseline, and to modify them as owner experience accumulates to have the car last 20 years unless the bill to keep it that long is approaching that of buying new.

I replaced the transaxle fluid at around 70k miles, and plan to replace it every 50k hereon in unless new data comes along. I bought the inverter coolant pump a year ago, and will put it in this autumn although the original is fine. I change oil twice a year with a good filter and high spec synthetic. This works out to be up to a 10k miles change interval. I checked my front pads this spring and found them at 8 mm, and the rotors in fine shape. I'll check again in a few years. Current car use is 15 -20k miles/year.

In short, I shoot for reasonable maintenance for a good chance at long life, not optimal or extreme. The most important thing is to keep an eye on Patrick, the king of maintenance.

Re: Transaxle Oil Analysis - My 99K Update

Hi Everyone,

Sorry to be so late getting back to this but as I promised, I have the third installment of the Redline D6 ATF test in my Prius. I passed 99K miles back in march and had a bit over 40K miles on this latest change so I changed it again and got another UOA done. The results seem to be very good. Here is the summary from Blackstone:

"This was one of the longest oil runs we've seen from this transaxle, yet wear metals all read acceptably low. Most wear metals are lower than we've seen in the past. Copper isn't at an all-time low here, though it's lower than last time and still lower than averages, so we don't think there's a problems with brass/bronze parts inside this transaxle. We don't see anything here that looks like a problem, so we're giving your Prius another clean bill of health at 40,000 miles. Nice report! "

I've also attached an image of the report. I think this is a good result and support the premise that the Redline D6 can be a good alternate fluid in this application. I'm going to stick with it from here onwards and extend my change intervals to around 50K miles.

Please let me know if anyone sees a concern with this data or has differing results to mine. Meanwhile, have a nice summer!

Steve

Hi,
I just had my D6 uoa'ed also.
It shows very good wear numbers like yours but the TAN (acid) was getting bad.
I stowed the sample in my garage for about 8 months before I sent it out and I think some condensation got in the bottle and possibly contaminated it skewing the TAN number.

I pulled the oem fluid at 5K and installed this D6 sample and ran it for 25K. I dumped it and re-installed fresh D6 which I will pull again and have sampled at 20k making total mileage on car approx. 50K.

I see there's no Tan report on your sample. Too bad as its a very important number.

BTW, Redline no longer recommends D6 for the Prius. They now recommend D4.
Thats why it no longer shows as a replacement on there website for WS.
I called Dave @ Redline and he did not know why (???) but did say D6 will run fine in the Prius they just now recommend D4.

I had a virgin sample of D6 uoa'ed also for baseline. They notated moisture in it also. I stowed that too so its just condensation.

Hi Ed,

Thanks for the data. Yes, there were posts earlier in one of these threads about the lower viscosity of D6 relative to Toyota WS. I think it marginally helps with the fuel economy to have a lower voscosity number while keeping a shear stable condition. But, I'm not an expert. I'm not too worried about it but now that you remind me, I may try buying the D4 for my next change in 50K miles just to see what happens to my mileage and driving feel.

16 pages-hmmm
So have their been any failures-member failures- not "friend of a friend told me"
of these transaxles? Any "friend of a friend" failures?
Thanks
Charlie
ps-61000 miles on 2006-debating $45 and 1 hour of work crawling under raised car.
No problems of than inverter cooler failure and lying service writer( other "water pump" leaking also-wanted $450 or so).Many Service writers around here-NOLA metro- are scammers-have been all my life.

There have been some 1st person reports on PC.

XS650- thanks.
I liked those bikes-Triumphs without the oil leaks-bit heavier different sound but fun bikes.
Haven't seen one on the road in 15-20 years.

Maybe I'll hunt the forum and read the reports. Search transaxle failure I guess.

Thanks
Charlie

Hi all,

I recently passed the 100k mi mark on my 2005 (Gen II) Prius and according the user's manual had the following services done: replace engine coolant; replace inverter coolant; replace spark plugs; replace transmission fluid. This was at 106k mi (I was a little behind in getting it done). When I dropped it off at the dealer, the service tech said to me, "We also recommend that you change the transaxle fluid." I said, "Is that different from the transmission fluid?" He said "Yes, but the two mix during driving." At the time I only had room in the budget for the $543 that the first four services cost, so I declined that maintenance and said I'll do it when I have money for it.

Now the car has 113k mi on it. I was reading through this thread and it seems the transaxle fluid/oil degrades the quickest (recommended change at 60k mi vs. the other three at 100k mi). I bought my Prius with 85k mi and I don't know if it was done before or not. I'm scheduling an appointment to have it changed in the next few days (along with the water pump according to the TSB I got in the mail). Will I be in trouble waiting this long to have it changed? Will it affect the new trans fluid that was just put in 6k mi before (because they mix)?

Prius transmission is the transaxle. There is just one mechanism and one fluid. I would look for another dealer that knows better what they are talking about. Good luck!

If the previous service receipt includes 4 quarts of WS and two washers then hopefully they have drained and filled the transaxle fluid correctly.