ATF fluid changes ARE Required.

Hypoid refers to the cut and alignment of the pinion and gear geometry and is almost universally used. A defense against noise and wear.
And many manufacturers no longer require gear oil and use atf in a hypoid system.
But if you are sure there are no hypoid geometry in a Prius i digress.
But I still contend the majority of break in wear comes from the differential area and requires early maintenance.

 

I am pretty sure the problems are:

1. Initial wear and left-over manufacturing debris and assembly. Even the best built gears are going to 'buff' their surfaces in the initial operation.
2. Sealant initial leaching and 'sealant beads' on the inside.

My testing suggests the 5,000 mile, early change helps but there is likely to be an optimum, early change interval and protocol.

To do a study right, we would need a transaxle sampling valve so we can draw a series of samples over the initial service. Ideally, use several Prius in different service profiles. Then map:

• particle sizes and density over time
• oil sample testing looking for silicon but all metrics
• viscosity

Pure speculation, I suspect there is a shorter service interval, ~500-1,000 miles with 2-4 cold soak cycles, that shows a peak population of larger particles before they get mashed down into finer material. A flush at this time could remove the initial, larger debris. But this debris may also serve as a 'lapping' compound to finish polishing the gear surfaces. What I don't know is how long this period should be. Regardless, oil testing suggests the initial oil replacements should be less than 30,000 miles.

Bob Wilson

 

By "details," I am assuming the new warranty transaxle replacement?

A sound that was rotational in nature started at 91K miles in 2011. It only occurred when the vehicle was in motion, and the loudness and rate (frequency) of the sound increased with vehicle speed. Now that I reflect, the closest sound I can think of is Space Invaders; no flying saucer sound, just the background sound as the aliens do their jumping jacks. No ATF drain/fill had ever been performed. No trauma to the transaxle from a: vehicle accident, curb, pot hole, road debris, etc.

Dropped the car off at a local Toyota dealership, paid the $100 diagnosis fee, and was later told the transaxle was going bad. No DTC codes, no Triangle of death, no nothing, other than that rotation sound, and a slight decrease in overall MPG. Decisions: new transaxle ($4K), used transaxle ($2k), sell Prius as is and buy a new or used car. But, I had a fairy tale ending. The service advisor called a week later, and informed me he got the transaxle covered under the longer California Emissions Warranty (10yr/150K miles emissions warranty), aka CARB Warranty. And I remember making this stink about the CARB warranty with corporate Toyota when I got the initial diagnosis from the dealer.
​

I still have a 8oz bottle sample of this used ATF-WS. Waiting for R&G Labs to send a sample analysis bottle to me. When these come, I'll be able to tell you better, as I am congested right now and can't smell anything. Don't recall any smell that stuck out at the time of the second ATF-WS drain/fill. Would you like a copy of this ATF-WS oil analysis when it comes? Maybe you and Prof Denenberg can incorporate it into your data set.

 

Give them a call but I've never had to use a sample bottle. Regardless, I would appreciate a copy of the report. I've left the database in the Yahoo Group 'Prius Technical Stuff' and would have no problem updating it with your sample.

Bob Wilson

 

If you did not buy an extended warranty what would the other 48 states have as a max warranty period for the tranny?

 

According to Toyota:

Powertrain Coverage[1]
60 months/60,000 miles (engine, transmission/transaxle, front-wheel-drive system, rear-wheel drive, seatbelts and airbags).​

I'm guessing the dealer made the argument that the failing transaxle would affect emissions or adversely affect the HV battery, thus it needs to be replaced under the CARB warranty, even though the powertrain warranty is over. I'm a happy camper that it was covered.

 

Purchased a 2007 Prius a couple of weeks ago. I have the full service records from Toyota so I am aware of all the work Toyota did to the car. Just changed the ATF tonight with Toyota ATF-WS. The odometer is at 92,777. This was the first Transaxle fluid change for this car. The work was done at night but I would call the color very dark burgundy and not black. But pretty darn close to black. It is normal for me to change fluids in a car when I purchase it. However, I've been reading on PriusChat about the transaxle oil change study and obviously this change was long overdue.

Some particles on the magnet were surprisingly large. Yes, most was just metal sludge but there were a few "nuggets" in there. Large enough to be trapped in the eye of a small needle.

There was another reason to do this oil change. I live at sea level and hills are restricted to overpasses. On a couple of drives I would hear the transmission sound as if I had dropped into too high of a gear (I know CVT but I'm trying to create an aural image here.) For instance I should have dropped into 2nd gear in a manual transmission but missed the gate and hit 4th instead. The engine sounded as if it was revving to maintain speed. This is an exaggeration but the sound was similiar. Maybe the oil change fixed it and maybe it didn't but on a short drive after the change the throttle response feels much improved and no sound of revving. Seat of the pants study but I'm much happier with the car now.

Oh and the last time the dealer changed the oil, prior to my purchase, they overfilled the crankcase. I had to let oil out. This is why I do all of my own maintenance. I can't believe that I drove off the lot without checking the oil level and didn't catch it until I got home.

The Prius, so far (2 weeks), has been a great car. This looks like it will be a fun one to own.

 

My dealer has a last chance person who checks all the fluid levels. Usually it is a little low. However several years ago they just dumped what ever quarts they had on the bench in the crank case. I then started bringing a 5 qt jug with the correct amount in it.

I will not change my own oil for liability reasons.

 

Changed my transaxle fluid at 49k. I had 3 people at the dealership tell me that I could not do it, that it requires a special machine and the fluid has to be at the right temperature. They finally sold me the crush washers and fluid and I changed the engine oil and transaxle oil at the same time.

 

Good for you. At least I had no resistance at the parts counter, the washers and fluid were readily available. Toyota really does a disservice to both owners and dealerships, with this head-in-the-sand attitude towards transaxle fluid changes.

 

I had no problem convincing my dealer to take $100 to drain and refill my Prius (4 times now) and when I showed them the lab report on the used ATF, they now suggest this job every 60k miles to all their Prius owners.

JeffD

 

The weird part is that a year or so ago I was in the exact same dealership to get the parts to do my wife's 2009 transaxle and they sold me the parts with no issue at all.

 

John the transmission in the Prius is an E CVT, and as such has no ratio changes what so ever. It has no reverse gear, and no neutral.
If you go to the link below and scroll to the bottom of the page you can play with the sliders on the model that control MG2, and the engine. The digital readouts will give engine, mg1, mg2, speeds, and direction with road speed. This is one of the best displays I have seen to show the operation of the transmission.
Toyota Prius - Power Split Device

John (Britprius)

 

I just bought an 09 Prius with 28k miles. I went out to look at the ATF and it is fluorescent pink/red and super clear. Is that normal after 28k miles? I know the first transaxle drain/fill is recommended in many forums around 30k to get rid of any metallic substances in there. Would everyone recommend I still do this right now even though the eyeball test would say this fluid is extremely healthy?

 

A finger dip in the fill hole tells you nothing. If you are sure it has not already been done...change it.

 

It was my lab tests that convinced our Prius ATF testing group (most of the others were testin Gen1 Prii) that doing the first refresh at 30k mile is a good idea followed by another every 60k miles. You can't really tell fluid condition from the color, it takes a $25-$30 lab test.

JeffD

 

I am nearing 30k maybe a month or so driving. Out of the 'free' maintenance period, so I can do oil and ATF change at non Toyota place if I want.

Does anyone have experience or could recommend independent shop in Long Island NY preferably Nassau county (south shore) to do the job? And, what should be a reasonable price either individually oil change and ATF change or the two service combined. All the other stuff dealer "recommend" at 30k is hogwash. I mean the car would be on the lift for the oil-change already, cover plastic is probably off, and drain and fill the transmission should be very little extra ...

thanks...

 

Having done a couple of transaxle fluid changes myself, I can give you some info. The parts you'll need:

4 liters (or qts) of Toyota ATF-WS fluid: $9.32 (each, in CAN dollars) (you'll need approx. 3.5 liters)
2 washers, for drain/fill bolts: $1.99
Total parts cost: $41.26

(prices from my last purchase)

Labour: if the car was up on hoist, half an hour, an hour at most? Whatever that costs.

It's an unusual fluid, and to avoid getting talked into using something else, likely simplest if you supply the fluid. You might also supply them with a clean/new funnel with 36" of clear tubing extension, say 3/8" diameter tubing. Mainly to avoid contamination.

The torque spec for both bolts is 29 ft/lb. They're both 10mm socket head cap screws (like a 10 mm Allen Key, but you should use a driver that can be snapped onto a torque wrench)

Proper level is achieved by just pouring in the new fluid with the car level, 'till it starts coming back out of the fill hole.

If you're toying with doing your own oil changes, this is no more difficult, just a bit different.

 

Thanks a lot for the info. I am not entertaining the idea of DIY mainly because I do not have a way to hoist the car. I know it is doable but then I have the old oil to take care of etc....

I just did not want to be taken advantage of.

I already had the pdf file (printed ....) so I have something in hand if service person try to bullshit me ... but was hoping some recommendation of a mechanic/shop in my "neighborhood" from fellow PriusChat-er...