DRAFT Transaxle Oil Testing Results

[Patrick Wong]

Originally Posted by shaun

...I was just wondering if the transmission pan that Bob dropped and replaced the seal/gasket for is specific to the Gen I Prius. When I called to get a quote on changing the fluid and seal from my local dealer, they said that the Gen II Prius doesn't have one to replace. Dropping the pan was not an option as it was a simple drain and fill.

Correct, only the Classic transaxle has a drain pan. Since you have G2, the needed parts include 4 US quarts of Toyota ATF WS and a couple of aluminum washers for the transaxle drain and fill plugs.

[satwood]

Originally Posted by dcoyne78

Over 23k thats a lot of shear the D6 starts at 6.4 at 100 C so thats about a 13.4 % loss in viscosity, was there any increase in fuel consumption due to the heavier fluid?

Hi, sorry I did not saee your question from last winter. Yes, my fuel consumption went down at the end but it also goes down in winter anyway so i can't tell you if there was any fluid impact. Now that it is summer again and I have another 10K on the next round, I'm back to over 50 easy so I don't see any obvious problems, so far...

[jdenenberg]

All,

I just did the third ATF refresh in my 2004 Prius at 180k miles. The results look great and are attached here. Bob Wilson Has analyzed these results in Prius_Technical_Discussion or MyHybridCar. My (and Bob's) thoughts after looking carefully at them is:

1. Do your first ATF refresh early at 30k miles to flush out some of the "Break-In" wear materials.
2. Then after another 60k miles do your second ATF refresh
3. After that you can consider stretching the interval out to perhaps as much as 90k miles (there is some question about the viscosity change beyond 60k miles, but the wear materials should be fine).

I have always used Toyota Type WS ATF in my Prius. Others have used other brands, but we have no laboratory data showing the safety or effectiveness of other ATF brands.

All of my ATF tests were done by R&G labs (formerly PDMA). Others have used Blackstone Labs, but it is difficult to make accurate comparisons as testing procedures vary between different labs.

JeffD

[snijd]

Very nice report. I noticed that the silicon amount dropped by about half with each change. Perhaps the next UOA will see something like 20ppm. Do you think you're still removing residual contamination, or are you also picking up a bit of dirt along the way? It just makes me wonder if three changes in fairly quick succession would also get you down to 35ppm, and thus remove a significant wear agent.

[jdenenberg]

Originally Posted by snijd

Very nice report. I noticed that the silicon amount dropped by about half with each change. Perhaps the next UOA will see something like 20ppm. Do you think you're still removing residual contamination, or are you also picking up a bit of dirt along the way? It just makes me wonder if three changes in fairly quick succession would also get you down to 35ppm, and thus remove a significant wear agent.

Bob has noted that there does seem to be a sealant leaching the silicon (and perhaps some iron) into the ATF. The leaching process requires time, temperature and perhaps turbulence, so short interval ATF exchanges may not reduce the amount of silicon in a later refresh.

One effect of multiple refreshes is the dilution of small amount used ATF that remains in the PSD after draining so there would be some benefit at the cost of some extra Type WS ATF ($$$). This, however, would not account for a factor of 2 in silicon content.

JeffD

[2009Prius]

Originally Posted by jdenenberg

.... Bob Wilson Has analyzed these results in Prius_Technical_Discussion or MyHybridCar. ...

Now in PriusChat too:

Transaxle oil, recent analysis

Have fun!