ZVW30 Transmission Oil Analysis

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by bwilson4web, Oct 2, 2009.

  1. bwilson4web

    bwilson4web i3 and Prime

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    I am a great fan of analyzing transmission oil because unlike engine oil, it tends to stay in service at least 10 times longer. Furthermore, earlier studies of transmission (aka., transaxle) oils revealed the NHW11 service interval needed to be shorter, 30k miles instead of 60k. The NHW20 using Type WS looks to be working fine at 60k miles.

    When I took my wife's ZVW30 in for the first change, I had the transmission oil changed and got a sample, about a cup. It was opaque but still smelled like oil. For sure, I wanted to remove the initial SI leached from the sealant as well as the early 'lapping' as the gears wear in. Also, I am very interested in seeing any evidence of oil oxidation (more about this later.)

    Here is the initial sample report and there will be updates in the future. Oh and one last thing.

    I am no longer in the business of collecting oil samples from others and sending them out to be tested. In the past that was the fastest way to collect a population of oil samples at different mileages to understand what was going on. But the ZVW30 is new, less than four months in North America.

    If you want to participate in this study, feel free but please arrange for your own samples to be send to a quality lab for analysis. I have history with R&G and they provide 40C and 100C viscosity testing, which I think is an important metric equal to the wear and additive content.

    Go here if you want to see a reference sample of Type WS and why transmission oil testing is important.

    Enjoy,
    Bob Wilson
     

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  2. bwilson4web

    bwilson4web i3 and Prime

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    Ok, this is the oil analysis that I'm interested in:
    [​IMG]

    Ok, the reason I'm interested is to find out how the viscosity decreases over time. I spoke with James, the lab tech, and we're going to do some special tests to look for micro-dieseling. Micro-dieseling is a type of oil oxidation. We're also going to check the particle load.

    ANALYSIS

    The goal is to estimate the miles to a 15% loss of viscosity:
    Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8
    0 C cSt 0mi cSt 5kmi % miles ~15% mi
    1 40 24.6 23.3 -5.3% 5 000 14 192
    2 100 5.5 5.3 -3.6% 5 000 20 625
    .
    This suggests the next change needs to be after 15-20k miles of service. This initial rate of viscosity loss is similar to rates seen with the NHW11s.

    Other experiments have shown the silicon is leached from the case sealant. The highest concentrations in the past, 227-258 ppm, suggests we've taken out half of the silicon and leached sealant elements.

    The iron, aluminum, copper, nickel, and manganese appear to be wear materials but some of them could be leached from the sealant. We'll need another sample closer to 15-20k miles to gain insights. Looking at iron, this rate .0042 ppm/mi is consistent with the .0037 ppm/mi seen with Type WS in an NHW20 transmission. We're probably seeing local spike due to early wear. The next test will give a better idea of the long term wear.

    I suspect the boron is boron nitride, an anti-friction additive, that is used up over time. Interesting, I see no evidence of anti-friction, molybdenum suggesting its other characteristics may cause material problems with these transmissions.

    It took about four months to reach 5,000 miles. At this rate, it will take a little over a year before taking our second change and analysis.

    Bob Wilson
     
  3. bwilson4web

    bwilson4web i3 and Prime

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    I've gotten the microscopic examination report:
    (see attached)

    We also had a particle count:
    4/ml - 99999
    6/ml - 9959
    14/ml - 18
    20/ml - 4
    30/ml - 2
    40/ml - 0
    Mostly we're seeing very small, very fine particles and not much in the larger sizes. These are not in the sizes that an ordinary filter would handle, ~14 u. The smaller particles would take a micro-filtration system and commercial ones are pretty expensive.

    The acid number is up a little, 1.49 vs. 1.41, we'll watch it over time. This is our primary indicator of micro-dieseling.

    Silicon leaching is evident but lets compare the sealant test, 8 months soaking Type WS in a jelly jar, values and a virgin Type WS sample with those from this change:
    Column 1 Column 2 Column 3 Column 4
    0 element virgin ZVW30 5k sealant
    1 Silicon 3 103 1280
    2 Boron 59 47 24
    3 Phosphorus 245 247 258
    4 Calcium 109 120 124
    5 Zinc 0 10 69
    .
    My thoughts:

    • silicon - sealant is the likely source being leached
    • boron - an additive to reduce friction, the loss when exposed to sealant is curious.
    • phosphorus - an additive, nothing remarkable, a formulation change?
    • calcium - normally an additive, a formulation change?
    • zinc - sealant is the likely source, one patent describes using zinc oxide to improve surface characteristics
    The red oxide observed may be from the sealant. Dow reports using "iron oxide" in some of their products and the sealant is red in color. However, there was no iron found in the sealant dish test (8 months soaking in a jelly jar.) Speculation on my part, sealant under stress may shed small particles.

    There are some reports from Amsoil sites claiming leaching of silicon sealants leads to foaming in oil. But I've not found anything specific.

    BOTTOM LINE - IS A 5K TRANSAXLE OIL CHANGE WORTH IT?

    This is what I'm after:

    • reduced rolling resistance - oil debris increases friction and generates local heat, the enemy of oil
    • viscosity tracking - oil wears and loses its ability to reduce drag and protect surfaces ... I want to understand the rate
    My early change removed some wear material and sealant leached compounds. Also, there appears to be ~5% viscosity loss after 5k miles. So I feel comfortable going 15k before my next change but this satisfies my curiosity.

    I'm not doing transaxle oil changes for extending the transaxle life. The ZVW30 transaxles have been out for less than six months and we have no failure history. The earlier NHW20 transaxles have been very robust with very few documented failures. The NHW11 had one go over 350k miles and the hand full of NHW11 failures have been electrical, not mechanical. But rolling drag is something I do worry about.

    My earliest hill roll-down tests showed a measurable reduction after an early transaxle oil change. Given it is a 'free' drag reduction, keeping the transaxle oil clean seems like a small price to pay. Not to worry, the used oil is recycled.

    Bob Wilson
     

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  4. dcoyne78

    dcoyne78 New Member

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    Here is another uoa on 2010 Prius transmission fluid. Aluminum is quite high in my analysis compared with Bob's. I plan to sample again at 23000 miles and hopefully this will be more in line with Bob's result. Silicon and viscosity are similar to Bob's result and iron is 30 ppm vs 21 ppm for Bob and copper is a similar level. I have changed out the fluid. pdf is attached.
     

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  5. jayman

    jayman Senior Member

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    Bob I agree with your comments regarding the additives in the oil

    Although the average person probably won't worry about it, if I had a 2010 Prius I'd do an early initial change, just as I did with my'04
     
  6. bwilson4web

    bwilson4web i3 and Prime

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    Excellent! Your 11,000 miles and my 5,000 miles means we can start to plot rates. But a couple of questions about the report:

    • OXID - how is this measured? The reason is I am concerned (Ok, paranoid) about micro-dieseling.
    • KF - huh? What is this?
    • FLASH - interesting, we need to send them a baseline sample.
    This is great!

    Bob Wilson
     
  7. dcoyne78

    dcoyne78 New Member

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    Hi Bob,

    I am not sure how oxidation is measured. KF is a Karl Fisher Water test and I am unsure how this relates to a % of water in the sample. The flashpoint test is a closed cup test, some labs use an open cup flashpoint test which tends to give a higher result. Terry Dyson gives a nice audio report which goes over anything to be concerned about, but the information in the audio report is not to be shared, only the pdf can be shared.

    For my test the Viscosity at 40 C was a little higher than in your test at 5k, which may just be statistical variation, but is unexpected. The Viscosity at 100 C was about 7.2 % lower than baseline so you may want to take yours out to about 28k to see if you get the 15% drop you are aiming for. I drive a little more than you, I will probably reach 23k in May or June and plan to test at that point (but I will just pull a sample from the fill hole) to see if my aluminum has dropped to more comfortable levels. Then I may test again at some mileage higher than your 23k test (if that is what you choose to do) maybe at a 35k interval (which would put me at 46.5k on my car). It depends a little on the results we see from our analyses and we can discuss it here.

    Thanks for all your research.

    Dennis
     
  8. dcoyne78

    dcoyne78 New Member

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    I am not quite sure this will answer your question (I am a little unclear on what you are asking.) The analysis is on the original transmission fluid that was installed at the factory (I believe that is true of the 5000 mile analysis done by Bob as well). So we cannot determine how a different fluid might perform except by testing. As far as I know there are no other fluids recommended for the Prius transmission. There are a few Toyota WS fluid substitutes (Amsoil, Redline, and Eneos come to mind) but in the case of the Amsoil ATL it is not recommended for the 2004 Prius. Until I get past 60000 miles I plan to use the OEM fluid, so the transmission was refilled with Toyota WS fluid at the dealership where I had the service performed for $68.
     
  9. rrolff

    rrolff Prius Surgeon

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    Where are you guys getting our oils changed? Most mechanics don't have the Toyota fluid - and even if you brought it in, I don't think many know how to fill - or that you need to pump it in....

    After this - I'll get our Lexus swapped...
     
  10. bwilson4web

    bwilson4web i3 and Prime

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    I'm staying with Toyota Type WS:

    • lowest viscosity - I've checked several alternate sources and their specifications indicate a higher viscosity. If I were in a hotter climate, say the desert SouthWest, I might consider a higher viscosity oil. But in our temperate climate, OEM is not just good enough, it is better than anything else I've found.
    • lessons from Amsoil - they claimed to have a Type T-IV compatible oil but the following Cu rates were excessive. Later I learned their additives are hostile to 'yellow metal', which include copper and bronze bushings.
    As for our friends in Canada, Alaska and colder climates, I would strongly suggest a block heater for the ICE and pan heater for the transaxle. The reason is viscosity increases with colder temperatures and increases the mechanical stress not only on the parts, more drag, but also on the oil itself.

    Bob Wilson
     
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  11. Philosophe

    Philosophe 2010 Prius owner

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    Bob, can you explain why? It is for the longevity of the transaxle or for FE? It the latter, what kind of fuel consumption difference are we talking about?
     
  12. brad_rules_man

    brad_rules_man Hybrid electric revolutionizer

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    Bob, if you can just be sure to let us know your final opinions, and maybe suggestions after you figure it all out. Are you suggesting it might be a good idea to have the trans-axle oil changed? Thanks for doing all the analysis, because I'm not sure I'd spend the $, but I'll definitely listen to you and spend the $ on changing it out.
     
  13. bwilson4web

    bwilson4web i3 and Prime

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    First we have to get some data and that means samples and testing. I preferred an early change to flush any residual manufacturing debris, which I had analyzed. It will take more samples to draw any conclusions. I don't think we'll really know for at least two years.

    Bob Wilson
     
  14. dcoyne78

    dcoyne78 New Member

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    My transmission fluid change was done at the Toyota dealer for $68.
     
  15. dcoyne78

    dcoyne78 New Member

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    I agree with Bob that we need more testing so if anyone wants to do it you can use the lab that Bob uses for about $20 (correct me if I wrong about this price). Right now we have two results one at 5000 and the second at 11500. I would recommend changing out the fluid early at 10k or even 5k like Bob did so that any early break-in metals are removed. For those that would prefer to wait and don't mind spending $20 and asking the mechanic to take a sample (you can get a sample kit from Blackstone for free), we could use other samples from 15k, 25k, etc and post the results on this thread. I also agree with Bob's comments elsewhere that the lab he uses is a better deal for transmission oil analysis than Blackstone because we get viscosity at 40 C and 100 C rather than just 100 C, but any analysis would be interesting.
     
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  16. bwilson4web

    bwilson4web i3 and Prime

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    With three samples, we can see more patterns:

    WEAR MATERIAL
    Column 1 Column 2 Column 3 Column 4 Column 5 Column 6
    0 service miles Si Al Fe Cu Zn
    1 0 2 1 1 0 0
    2 5000 103 19 21 16 10
    3 11520 106 54 30 19 9
    4 19687 132 110 55 21 14
    bwilson4web, dcoyne78, tumbleweed

    In normal wear, we expect to see an initial jump followed by a longer period of low increases. The initial service 'laps' or 'polishes' the moving parts that come in contact. We are less happy to see a rate that remains constant and get concerned if we see a rate that increases over time.

    The silicon is probably leaching out of the case sealant. Other testing involving just transaxle sealant in a sample jar confirmed this. The data suggests the rate has tapered off but we'll need samples at +20k miles to draw any conclusions.

    Aluminum is unexpectedly high. In ordinary samples, aluminum and silicon are the signatures of grit getting into the transaxle. But again, we need follow up samples to see what is happening. Speculation, the transaxle oil pump may have wear surfaces. We'll need to watch this one.

    Iron and copper shows an initial wear rate that appears to have tapered off. This looks normal.

    OIL ADDITIVES
    Column 1 Column 2 Column 3 Column 4
    0 service miles P Ca B
    1 0 245 109 59
    2 5000 247 120 47
    3 11520 253 85 49
    4 19687 288 143 46
    bwilson4web, dcoyne78, tumbleweed

    With additives we expect to see high levels initially that decrease over time by either capture in deposits or have an initial decrease and remain at a constant level.

    The dramatic changes in calcium suggests an oil formulation change. However, we can't rule out different lab sensitivities (WITHOUT CALLING EITHER INTO DOUBT!!!) We'll need more samples and possibly understanding the manufacture date to track this. The bwilson4web Prius was manufactured in April 2009. But we've seen an increase in calcium over service life with the earlier transaxle oil studies.

    The boron, probably boron nitride, was probably initially deposited on rolling contact surfaces and then appears to hold constant ... a good thing.

    Zinc is normally part of an additive. Given the change from the reference sample, it again suggests an oil formulation change.

    VISCOSITY
    Column 1 Column 2 Column 3 Column 4
    0 service miles cSt 40C cSt 100C Vis. Index
    1 0 24.6 5.5 171
    2 5000 23.3 5.3 171
    3 11520 23.5 5.1 152
    4 19687 4.78
    bwilson4web, dcoyne78, tumbleweed

    We are seeing some viscosity loss but the rates appear modest. However, if there are changes being made in the transaxle oil, we may see it in the oil viscosity too. Again, we'll need additional samples to understand what is going on. However, if I had a new transaxle that was all 'gears' and no longer had the 'silent chain,' I would see a lighter viscosity at 100C as being a good thing.

    Now we can start looking at one viscosity, 100C, as a function of miles:
    Column 1 Column 2 Column 3
    0 service miles cSt 100C decrease %
    1 0 5.5 0.0%
    2 5000 5.3 3.6%
    3 11520 5.1 7.2%
    4 19687 4.78 13.1%
    bwilson4web, dcoyne78, tumbleweed

    The target is a 15% loss of viscosity means the oil needs to be changed. My earlier straight-line suggested 15,000 miles and I'm waiting to 20,000 miles before my second change (at 12.5k miles, I have about 7-9 months before the next change.) Prius friend 'tumbleweed' is showing something between 20-25k miles may be the optimum target. I may extend my next change to 20k service miles, 25k total.

    CONCLUSION
    Three samples were taken out early, as much a flush and baseline as anything else. However, based upon these samples, something interesting may be going on. Possibly an oil formulation change and an interesting aluminum wear pattern needs watching. We do have a better understanding of when viscosity changes would mandate a change, 20-25k miles.

    Bob Wilson
     
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  17. dcoyne78

    dcoyne78 New Member

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    Thanks for this info Bob, I agree that some of the differences may be due to using different labs, though there is agreement on many of the oil additives and such. Wasn't the 100 C Viscosity 5.3 on your analysis?
     
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  18. tumbleweed

    tumbleweed Senior Member

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    This is the UOA from my transaxle after 19,687 miles.
     

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  19. ksstathead

    ksstathead Active Member

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    Looking at the maintenance log that came with my ZVW30, no change interval is given for "automatic transmission" fluid. Rather, it calls for inspection of the fluid every 30,000 miles or 36 months.

    Anyone aware of more explicit guidance from Toyota?

    I am approaching the 10,000 mile mark after 7 months, and have no imminent plans to change or sample the fluid, though I will reconsider as this thread develops.
     
  20. bwilson4web

    bwilson4web i3 and Prime

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    I know but we didn't really have much guidance for the NHW11, NHW20 and now the ZVW30. But unlike Toyota, we own our cars and want them to last a long, long time. So we are conducting the experiment, actually sending oil samples for analysis and <ZUT ALORS> sharing the results!

    Bob Wilson
     
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