UOA Question

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by wick1ert, Oct 14, 2010.

  1. wick1ert

    wick1ert Senior Member

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    Ok, so I just did my 2nd OC over the weekend at around 10k miles since the last one. They put me at a high severity, I believe due to the fuel dilution part.

    The car engine was not warm and neither was the oil when I did the change. I turned the car on, let it go through it's initial warm-up cycle, then pulled it onto the ramps. Would that possibly cause this higher reading?

    The rest didn't seem all that bad. I had the regular OEM oil filter, Amsoil 0W20 synthetic (25k stuff), and it'd been just under 10 months since the last change.

    For those more adept at reading these, yes, it says "10" for the lube time, that was supposed to be 10k because I had a brain fart and didn't fill it out all the way lol. I figured 10k was close enough for an estimate because I couldn't find the last one with the mileage on it.

    Thoughts? Comments?
     

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  2. spiderman

    spiderman wretched

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    This is the first one I have seen from OAI, the rest from Blackstone. So what was the mileage at the time of the analysis? 15K? I suspose that the rings might not be entirely seated as these engines have an easier life but still... Doesn't mean that a head gasket couldn't be leaking. Anyway, if it were me, I would probably use regular syn (so as not to waste really good oil) for about 5-7K and have it read by Blackstone to compare readings.
     
  3. wick1ert

    wick1ert Senior Member

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    Correct, I am just over 15k on the car right now. I only used OAI because that's who Amsoil went through. I think I'll switch to blackstone going forward, though, since I've got a sample jar from them at the house also. I might start doing them on the Harley if blackstone offers their service on those too.

    I've still got about 3.5 qts of Amsoil at home, and since I use that for my Harley as well, I will probably continue to put it in the Prius. It's about the same price as what the Toyota oil is for the car for me too.

    I think I will do a spring time change, as that should put me around 5-7k after this one. That should give me a good idea as to whether it appears things are getting better / worse / staying the same. I'm not a fan of changing oil in the winter months (I know, it's not nearly as cold as Alaska).
     
  4. spiderman

    spiderman wretched

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    Yeah, I timed my next change @ 20K right around next April when things start to warm up a bit here. That will be 7.5K total miles. I will send in a sample at that time. Nothing worse than having slush far in your face while changing oil!

    I misspoke about the head gasket... that would lead to water/coolant contamination not fuel contamination. Lond day.
     
  5. tochatihu

    tochatihu Senior Member

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    From what has been posted here in the past, it seems that Prius oil shows high fuel dilution (above 1%) about half the time. I don't think we have ever worked out whether the oil sampling procedure is responsible for that. As you have described your sampling, I suppose that it probably did contribute to fuel dilution.

    Early UOA on Prius engines generally show elevated iron and copper. As your silicon was also high, I suggest that you confirm that te engine air filter is clean and working properly.
     
  6. rumpledoll

    rumpledoll Member

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    Yes, a cold start can result in a higher fuel dilution reading. In a cold engine, more fuel is needed to run the engine. In the old days a choke on a carburetor would do this, in modern cars the ECU orders the fuel injectors to inject more fuel.

    Some of this fuel is not burned and some of that is washed past the piston rings into the oil. This can results in a higher fuel dilution reading than one taking from hot oil, or oil that was hot, allowed to cool and then a sample taken.

    The UOA is a good, still plenty of life in the oil as indicated by the strong TBN at 10,000 miles. More evidence that a 10,000 mile OCI is easily done by our cars.

    Rumple

     
  7. wick1ert

    wick1ert Senior Member

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    Thanks guys! It sounds to me like the fuel dilution probably is due to the cold engine having just gone through it's warm up cycle.

    As far as the air filter, it's good as I replaced it back in May, about 5k miles ago. I will double check it over the weekend when I pump the air pressures back up in the tires. The dealership had it to check the TPMS issue I was having, and I am sure they set the pressures back down.

    I have the quick valve installed for when I do the oil changes, so I opened that up, let the oil flow for about 10-15 seconds, then took the sample that way. Probably not the greatest option, but it worked great. Way easier than getting the tube down into the pan and using that little hand pump to do it.

    Appreciate the feedback from everyone.
     
  8. Mr.Vanvandenburg

    Mr.Vanvandenburg New Member

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    Having only a 07 pkg 2 thanks for the invitation for comments. The iron is a little high also, but the car is new. This to me doesn't support the 10k change interval in your case. The fuel burns off in longer use, but not necessarily does it do so, and changing sooner gets rid of the damage the fuel has done to the oil. Pretty much what they said when they said the oil needs changing NOW. The other issue is about silicon. Ford is extending air filter changes to 100k, and there was a rather convincing analysis done on that topic I read. I should have saved it but didn't. Essentially it concluded changing air filters too early decreases the efficiency. The theory is the new filter filters less well than a partially filled filter. I don't know if I agree with that but in my case I am trying for 50k on the original air filter. At 30k it doesn't look very dirty at all, so of course it depends on conditions. That company seems to have a nice test, thanks for sharing the info.
     
  9. wick1ert

    wick1ert Senior Member

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    I replaced my air filter at about 12k this last may. It was more a piece of mind at that point. It didn't look bad at all, really. I will probably extend this next time, with an annual check to make sure it's still in good shape.

    I think the issue on air filtration is two-fold. While a new filter might not catch as many fine particles, it allows for proper air flow to the engine. A dirtier one, which has partial clogs (for lack of better word) will catch more dirt, but also restrict air flow to the engine because it can't get through the mess as easily. If they had a filter that filtered smaller particles, it would dirty quicker and probably need replaced sooner. I guess it's sort of like a give-take scenario - similar to the MERV ratings on HVAC filters (higher MERV, smaller particles caught, quicker it gets dirty).

    Most of my drives are 4.5-5 miles each way, so I can see how the fuel dilution may be a tad higher than what they prefer from the information in an above post. However, you can tell with 1k/month roughly since I got the car (end of June 2009), there are also some longer trips in there as well.
     
  10. bwilson4web

    bwilson4web BMW i3 and Model 3

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    It is my practice when changing oil, a brand or weight, is to send a virgin sample to the lab for testing. This way the subsequent change after service reflects what the engine (or transmission in my case) did to the oil. Without a baseline, it is difficult to really interpret the results.

    Perhaps you might find a link to the Amsoil used in the first change. If so, we can then see the difference 10,000 miles made in the oil.

    Thanks,
    Bob Wilson
     
  11. Former Member 68813

    Former Member 68813 Senior Member

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    Good tip on air filters, makes sense. But I have to disagree with what you said about oil.

    24 ppm Fe or 12 ppm Al is not high for 10,000 miles. I would say average. Ppm per mile is what counts and not absolute number.

    His silicon is from seals, it decreased compared to the first UOA, and it is not contamination (wear metals would be much higher).

    His gas in oil is from idling on cold engine before sampling. Common mistake. I made it once in Subaru and got 5% fuel on report.

    That company is cheap but unreliable. I used them in the past and sent me some garbage results (like 0 ppm Fe in 6,000 miles) that turned out to be very incorrect after retesting.

    I'm personally not doing any UOA anymore. Interesting hobby but unnecessary for NA engines seeing light to moderate use (or very light in Prius) and modern oils that are way better than just several years ago.
     
  12. wick1ert

    wick1ert Senior Member

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    Thanks FJ. My main concern was the fuel dilution part. And from what I've gathered, it is definitely from the idle warm-up cycle before changing. The first OC was done after driving 60 miles and then the car cooled down about 15 mins first.

    From what the different OA places say (and why wouldn't they?), it's a great way to catch an issue before it becomes really bad. Considering the longer OCI, it's a nice piece of mind for me, also. If it helps me convince people that 3k OCI are wasteful, then all the more reason to have the reports too.
     
  13. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I'm only doing it for my wife's ZVW30 and my NHW11 transmissions.

    Over a 2-3 year period, a lot of wonderful folks donated transaxle oil samples and I was able to analyze enough to see the real change interval:

    • ~30k :: NHW11
    • ~60k :: NHW20 (Thanks Jeffry)
    • <tbd> :: ZVW30 (wife's car)
    What we are finding is:

    1. < 15k miles -- do the initial oil change to remove the bulk of sealant leaching, manufacturing scruff, and gear lapping. I did my wife's transaxle oil change concurrent with the first oil change and am glad! The straight line viscosity indicated 15 k was the max and it had a boat load of larger grain material in it. The early change flushed those particles out.
    2. 30-60k miles -- second change (NHW11 and NHW20) the part that can not be drained and last of the initial sealant leaching
    3. 60-90k miles -- third change (NHW20) appears to be a stable region and may be extended further
    I have another 5 k miles to put on my wife's ZVW30 before I can project the next change interval. But given the 'chain' is gone, I suspect we will eventually see very high change intervals . . . 100 k miles or more.

    I have to admit I've never been a great fan of engine oil change analysis for our Prius for the same reasons you mentioned, our engines are 'loafing.' They spend a significant time off and the MG1 start sequence could not hardly be gentler. Yet the recommended change intervals are such that our engines are all but running on virgin oil most of their lives.

    Now my NHW11 has evidence of 'varnish' but it had that the day I picked it up with 49,300 miles. Given it came from Texas, I know how that happened!

    No, my interest is in the transmission because all power to the wheels has to pass through it. If we can minimize losses here, not only will we see a long-term, efficiency improvement but this terribly expensive part might go long enough that the wheels fall off first. <GRINS>

    Bob Wilson
     
  14. Mr.Vanvandenburg

    Mr.Vanvandenburg New Member

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    I am not sure what they said about air filtration was right, and can't find the article. The air filter is supposed to be sized for not reducing the air flow enough to cause problems over a long interval, like the Ford 100k or "lifetime." So even if clogged say 30%, the flow still is more than enough to satisfy the engine. Like oil I tended to change air filters more often than most folks. I am trying it out longer this time, haven't seen any decrease in power, mileage yet.
     
  15. vinnie97

    vinnie97 Whatever Works

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    Bob, do you think 5K is too early to change transaxle fluid? I'm highly considering it in light of your informative findings (along with a second oil change, the first being done at 1700...and then I'll stick to 7500-mile/6-month intervals thereafter).
     
  16. Mr.Vanvandenburg

    Mr.Vanvandenburg New Member

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    I was wrong about the Fe, it is over 10k as you say, and pretty normal. Some oil guys on other sites would still say 12 over 5k is a little high. Not sure what fuel does to oil, if anything, after it burns off. I think there are discussions about chemical changes to the oil that aren't reversed by burning the most volatiles off. In any case I like others have things to do besides care for my car. I tend to overdo the oil changes on, for me, an expensive purchase, to err on the safe side.
     
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