Changing Transaxle oil

Yes, the shavings were very fine... Interestingly, after I cleaned those off, right down on the surface of the magnet there were three larger pieces of iron shaving. They were about 3mm long and as wide as a mechanical pencil lead. I figure they were deposited (or attracted) first by the magnet early on in the life of the transaxle (perhaps they wore off during the break-in period), and then the numerous finer shavings accumulated on top.

 

Am I the only one who read bullet point #3 on galaxee's post? You know ... the stickey just above this thread? under "What service you need and what service you DON'T need?

Like here hubby (a Prius specialist) says, "you CAN change it prior to 100K miles, ... but there's no need".
Just curious

http://priuschat.com/forums/care-ma...70-what-services-you-need-what-you-don-t.html

In case you can't find it.

3. transaxle fluid
there is no way to "flush" the trans on a prius. if someone tries to sell you this, run. they can drain and fill, however. the fluid is expensive and is supposed to go 100k, but you can never go wrong changing it early. in most cases it isn't necessary. this is the same fluid that goes into a tundra for 100k under towing conditions. the only complication you might see is again due to tech error- using the wrong fluid or not filling all the way.

 

I had the fluid from my 2004 tested at 32K miles, and the viscosity was reduced ~15% from new. The fluid also contained significant silicon (indicative of dirt) as well as wear metal content. Since it costs me ~$25 or less to change the transaxle fluid, I don't mind changing it periodically.

If you have to pay big $$ at the dealer to have this done, I can see why you might hesitate.

 

Hi.
I am a new and isolated owner of a 2004 Prius in Dominican Republic. No dealer sells or repair this wonderful machine here, I bought in Miami. I have to do myself all the maintenance. Lately, I have a message in the dash: maintenance required. I made the change of engine oil, thinking that it could be. But I still have the same message and I have no user booklet to tell me the clue. Could it be possible that the transaxle is low on oil?.

Waiting for your help. Thanks.

Jean

 

Hi Jean,

The MAINT REQD light is just based on an odometer timer. It will come on momentarily 4,500 miles after it was last reset. It will come on solid 5,000 miles after it was last reset. The point of the light is to encourage you to change the engine oil and oil filter.

See the following string for instructions about how to reset.
http://priuschat.com/forums/prius-main-forum/42548-maint-reqd-light-seriously-toyota.html

 

I don't know if it is beneficial or not to change the transaxle oil before 100,000 miles. I was inspired to do it partly by Art's Automotive (who do it every 30,000 miles for their customers-- see Art's Automotive - 30K Service, 2nd Generation Prius ) and partly by the relatively low cost ($22.44 for parts).

 

Hey Patric, where in OC did you get your fluid "tested" for viscosity ? It's just not very common for a service tech to maintain / buy a tester, but there are several viscosity testers made. If the fluid isn't the same temperature as required by SAE when it's tested then you'd expect it to be 15% or so different. Also, a garage gets it's bread & butter by selling services to you, whether it's because you reached "X" amount of miles, or because a color's not quite right, or they say they did some kind of "test" that says you really really need a service. Let's face it, that's always suspect when service providers say that a fluid that's suposet to lasts "X" amount of time is defective / worn out before its time.

 

I've attached the results of my viscosity test, taken at 32,755 miles. The test was performed by a Tampa, FL lab:
PdMA Corporation - electric motor testing, oil analysis

Bob Wilson previously had this same lab test "virgin" Toyota ATF WS. That sample of new oil showed the following viscosity results:

LUBE DATA​

Viscosity @ 40'C cSt 24.6​

Viscosity @ 100'C cSt 5.5

The viscosity drop is of some concern; more important to me is the silicon and iron wear metal content in the used fluid.

 

Silicon contamination ~ isn't that glass/sand? Seems like iron is also a trace element in sand. Did they say how common that type of comtamination is? ... or speculate on where / how it would get in there? By how it got in there, I mean, how the silicon got inside the transaxle case. Either the case was contaminated prior to first being filled at the factory, or the lube was contaminated either prior to going into the case or after removal ... because the element can't simply grow out of nothing. Weird, and worthy of Sherlock Holms.

 

The used fluid test results are representative of used fluid samples tested by other Prius owners, giving due allowance for miles traveled on the fluid. It is unclear whether the silicon (i.e., dirt) is entering the transaxle via the axleshaft seals, or whether it might be leaching from the orange sealant that Toyota uses to seal the transaxle case. The transaxle maintains a partial vacuum when it has cooled down; perhaps this is encouraging some entry of dirt.

Regarding the iron wear metal content, visible evidence of this is provided in the photos that jreed provided earlier in the string; note the ferrous metal powder that had accumulated on the magnet. This is the iron that is showing up in the used fluid.

Since the Prius 2G transaxle has 500VAC on the motor generator stator windings, and based upon the used fluid testing, I have come to the conclusion that it is good preventive maintenance practice to change out the 2G transaxle fluid periodically (i.e., no later than 60K mile intervals) to get rid of the wear metal accumulation in the fluid. Reasonable people may disagree on this point; I only seek to provide group members with available info and data, then each person can make up his/her mind on that subject.

 

Patrick has covered the important parts and it remains something that has puzzled me for sometime. My early transaxle survey suggests those who live in more rural and agricultural areas tend to have higher amounts of silicon-aluminum. It turns out that silicon-aluminum ratios tend to follow the ratio found in the surrounding soils. But the hypothesis of sealant leaching SI is under testing.

In December 2007, I coated the bottom of a shallow jelly jar about the diameter of a Petri dish with sealant and gave it a couple of weeks to dry. Then the end of December, I filled one with virgin Type WS oil and have carried it around in my car under the rear glass so it has both mechanical and thermal cycles. Not perfect, I'm planning to send it for analysis soon.

I am also thinking about how to test for aerated transaxle oil and micro-dieseling. What can happen is small air bubbles in the gears can come under enough pressure that the small air bubbles ignite, like a diesel engine. Not only will there be the stresses from these small burnings but also the leftover products of combustion including a growing accumulation of soot. Some of the Blackstone analysis of transaxle oil includes the pH, a primary indication of combustion products.

I would recommend reading some of the literature including "Practicing Oil Analysis Magazine." My current thought is to look at something called 'ultra filtration' but this is a difficult problem.

Ultra filtration is an order of magnitude beyond ordinary engine oil filters and typically depends upon a separate filter loop that handles particles down to 2-3 microns. Today, most ultra filtration is handled by an oil cart that is wheeled up to the equipment. There is German company and Amsoil both sell vehicle based systems but the German system cost is very high and I've not been able to find much about the Amsoil system.

One thing for sure, changing my transaxle oil measurably reduced the cold, rolling resistance. But as the oil warms, it takes about 30 minutes to reach the new level, the viscosity goes down. Some of this warming is from mechanical 'working' of the oil; some from waste heat from MG1/MG2; and some transfered from the engine block to the transaxle case. As a general rule of thumb, the oil viscosity and friction goes down as it warms.

Almost all oils have variable amounts of additives and some of those additives are not 'friendly' to metals and materials in our transaxle. The test data from Amsoil ATF shows that it preserves the initial Type T-IV viscosity but promotes increasing copper content. We do not know if the copper comes from a chemical or mechanical mechanism but the high copper content is real and proportional to usage. Please do not test Amsoil ATF unless you are prepared to perform a number of intermediate samples incase the higher copper content shows up again.

GOOD LUCK!
Bob Wilson

ps. Blackstone includes the pH measurement, a great tool for oils exposed to combustion products. PdMA for an extra $5 will perform a pair of 40C/100C viscosity measurements that are best for testing mechanical oils. A subtle difference, I prefer a gear test for transaxle oil.

 

A little late into this thread, but here are more transaxle
fluid change pix/writeups:
_ http://techno-fandom.org/~hobbit/cars/maint50k/
_ http://techno-fandom.org/~hobbit/cars/nehg-0826/
When I did mine I did it the "hard way" by shifting the inverter,
but learned a bit more about what's under it in the process.
When we did Jesse's Classic [RIP...] I finally bought a clue
and attached a nice long hunk of hose to the funnel.
.
_H*

 

Patrick

My biggest regret now was not sending off the first cvt fluid change for analysis. Awhile back, htmlspinner changed his cvt fluid and it was pretty bad.

Given the extremely high replacement cost of a cvt should it happen to fail, it's cheap insurance. I recommend an early initial change, to get the worst of the crap out.

When I first changed my cvt fluid, it was already dark in color, and the magnet had fuzz on it. Subsequent changes the fluid has remained almost-new looking, and the magnet has stayed clean

jay

 

Hi Jay,

What is your odometer reading now and how frequently do you change the transaxle fluid? Thanks.

 

the transaxle apparently operates under vacuum- DH doesn't expect it to be sucking in air. but he has not had a spare breather plug to play with, either.

dirt wouldn't get in through axle seals.

the transmission sealant will dissolve in ATF if it contacts the fluid before it cures. it will not dissolve in ATF, obviously, once it has completely cured.

 

Patrick

A bit over 148,000 km. After the initial cvt fluid change at around 12,000 km, I started doing it every fall. This has worked out to around 20,000-40,000 km range

It helps that at my hobby farm I have a ramp - of sorts - built from old railway ties. I first did Sonotubes as we have frost here in winter, didn't want the structure to move. Poured 8 inches of concrete with rebar. I put the ties on top of the cement pad

I designed the ramp portion shallow enough so even my Prius can creep up with very minor scraping. The top is perfectly level, and I have enough clearance underneath to *almost* sit up

In hindsight, I would have made the ramp from steel and just used my welder. The ties were free, but the backbreaking work with them wasn't worth it.

I've done the cvt fluid change 5 times now, still using the original crush washers. Seems ok so far. Not sure if necessary - or even advised - but I also wrap a couple turns of teflon tape on the threads before snugging the drain/fill back up

jay

 

N

I guess that would depend on the fluid. Most RTV's are attacked by PAO's unless that red glop, which it appears is what Toyota uses.

When GM first switched the pickup trucks rear axle to factory fill synthetic, they had to go with a regular gasket instead of rtv, due to the leaks.

j

 

That is why I left the jars upside down with the lids off. The sealant says "24 hours" but I exceeded that by a factor of 7.

BTW, the sample in the jelly jar has somewhat darkened (or I'm going blind.) Regardless, I look forward to the test results.

Here in North Alabama the 'yellow season' has ended as the pine trees drop the parts that emit pollen. I'll pickup a fresh air filter and do my 'spring' maintenance including oil changes.

I am thinking about checking the wheel bearings and possibly replacing them. They have over 100,000 miles and though 'sealed', they came from north-central Texas.

Bob Wilson

 

Hi Bob,

Do you notice any noise coming from the wheel bearings? If not why worry?

A general question for those who have changed transaxle fluid with a pump instead of a funnel: You probably have noticed that the Toyota ATF comes in quart bottles with an unusually large diameter threaded opening. Were you able to find a pump that screws into that threaded opening? If so please advise where you bought this and the approx. cost.

The reason that I ask is because I took a look at my HiHy (w/30K miles) today, trying to see how difficult it will be to drain/replace the ATF WS. I'll need to use a pump for both the transaxle and the rear motor generator. The transaxle drain and fill plugs are on the passenger side of the case, near the passenger-side axle shaft opening. Hence it is necessary to get completely under the vehicle to reach those plugs, unlike Prius which has much easier access near the front.

 

Patrick

Up here, the Toyota dealer sells WS is 4 litre tin containers. I use a gear oil pump intended to pump oil into a stern drive unit, cost around $14

jay