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Oil burning prevention pondering

Discussion in 'Gen 3 Prius Technical Discussion' started by nick31, Feb 14, 2019.

  1. nick31

    nick31 Member

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    Ok so bear with my uneducated thoughts for a minute.

    We know that 2zr-fxe and 2zr-fe (and almost any newish Toyota engine) start to burn oil with a higher mileage.
    They burn oil because of the small piston oil drain holes and a narrow bottom ring spacing.
    These holes and ring get fully blocked by the carbon/gunk/polymers that are by-product of the oil/gas burning and oil not able to withstand high temperature in the cylinder.
    The blockage increases slowly at first and exponentially after some point (it didn't burn a week ago and now it burns a quarter per 1k mi).
    Since there is little we can do about gas (use ethanol-free-super-clean-racing gas maybe?), let's think about oil.
    We need to reduce excessive oil in the intake with the help of the pcv catch can.
    We need to use oil with a low NOACK so that it doesn't evaporate that easy and keeps its properties.
    We need to use oil that doesn't polymerize and doesn't form a high amount of deposits on the rings and pistons.

    It probably won't be any of the expensive synthetic oils you can find in your nearest automotive store. And most likely it will not be available in 0w20.
    Toyota Australia allows to use almost any weight oil in the 2zr-fxe. It is written in the Australian market maintenance manual. IMO 0w20 is mandatory in the USA because of the CAFE, energy efficiency and MPG promises (so that Toyota would avoid false advertising lawsuits). Engine is still the same.

    That makes me think that we can actually find some oils that will not be leaving deposits on the rings/pistons.
    Enter PQIA and Oil tests.

    We can check oil NOACK at PQIA. The second link presents a "catalog" of the alternatively-tested oils. Regretfully majority of these oils are not available in the USA and you also have to use google translate. They use a similar to or harsher than NOACK test to check for deposits and polymerization that otherwise stay in the pistons and rings.

    Let me know what you think.
     
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  2. bisco

    bisco cookie crumbler

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    i'm using mobil one, is that okay?
     
  3. nick31

    nick31 Member

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    I wish I knew (n)
     
  4. bisco

    bisco cookie crumbler

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  5. Mendel Leisk

    Mendel Leisk Senior Member

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    Some possible contributors:

    1. Cylinder temperatures increased by progressively clogging Exhaust Gas Recirculation circuit.

    2. Oil in the cylinder increased by Positive Crankcase Ventilation design.

    3. 10K mile oil change interval.
     
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  6. mjoo

    mjoo Senior Member

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    It wouldn't be that much more time and money to also do a piston soak at the same time as changing spark plugs or cleaning the EGR. Then you've covered all your bases. Just saying...

    Pixel XL ?
     
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  7. orenji

    orenji Senior Member

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    I agree with OP with what they have stated. But IMO the design of the engine is not the issue with the oil burning. It’s the weight of oil that is being used. As the OP stated, CAFE standards is an issue. Almost every new car uses OW-20 oil. This is so the manufactures receive credits in meeting the overall MPG standards set by CAFE. Every MPG increase is important to the manufactures. The use of thin oil helps achieve higher MPGs.
    But look in other parts of the world, and you can use a 30,40 and a 50 weight oil. Why is that not being mentioned in the USA version manual?

    I have been using Mobil 1 oil 0W-40 and have no issues. Also Mobil 0W-40 is the only true synthetic oil with the Mobil 1 name.
     
  8. Grit

    Grit Senior Member

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    A lot of people here believe it's not worth buying ethanol free gas because it's only a 3% gain when filling up w/E0 compared to E10. They don't factor in what by product will be left behind such as blow by because they won't be driving their prius into the ground so I'll save you some time if you decide to go into that discussion of the benefits of E0 vs E10.
     
  9. farmecologist

    farmecologist Senior Member

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    Another thread mentioned that 'Seafoam usage prior to an oil change' fixed their oil consumption. Anther thread mentioned that '6 tanks with Techron added to it' fixed their oil consumption. Another thread mentioned that 'piston soaks' fixed their oil consumption. Etc, etc...

    I have a healthy skepticism of all of these mitigations because they are usually not repeatable. However, I have added some of the above to my "it probably cant hurt" list of things to try.

    Many of us have tried other things to fix/mitigate oil consumption to no avail, and many of us have given up and have just decided to check the oil more frequently and top up ( myself included ). (y)

    But then again...it doesn't hurt to ponder what the root cause might be. Who knows, maybe someone will have a breakthrough at some point, but I doubt it. I think oil type has been discussed in the past as a possible root cause but was shot down? Oil change interval would be more likely. Some also seem to think an oil catch can may be the answer..along with frequent cleaning of the EGR circuit and cleaning of the intake manifold, etc...theories abound.
     
    #9 farmecologist, Feb 15, 2019
    Last edited: Feb 15, 2019
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  10. nick31

    nick31 Member

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    Good point, however proper piston soak requires more than a day (successful one was 3 days long; the cleaner has to get to the 3rd ring; you have to keep watching that cleaner covers the piston etc etc) and there is always a danger of hydro-locking the engine. It's a bit dangerous process without a 100% guarantee of the positive outcome. IMO this is a last resort. I would probably use Techron every other tank or 2 to mitigate the issue somehow.

    True, however take a look at the picture in the attachment. This oil did much better than other oils, but it's not the best. I am starting to think that a good mineral/blend oil is actually what we may need. None of that PAO stuff that polymerizes on the pistons/rings. Conventional/blend oil usually does well on the heat test. PYB 10w30 with noack of 4.4% comes to mind, however it was not tested.

    The root cause is well know: poorly designed pistons and rings (or pistons and rings designed for "ideal" oil). The solution is a costly replacement OR the oil that will not clog the piston drain holes. Essentially the oil that is able to withstand high cylinder temperatures without leaving (much) deposits or polymerizing.

    What do you think?
     

    Attached Files:

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  11. orenji

    orenji Senior Member

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    Not clear on what I am looking at in the attached picture??
     
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  12. mjoo

    mjoo Senior Member

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    No hydro-locking danger with the spark plugs out. Just crank the engine without plugs and with the pump and ignition fuses removed. Or syphon it with a mityvac.


    Pixel XL ?
     
  13. nick31

    nick31 Member

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    Oil heated to the temperature between 250c and 380c to verify if it polymerizes and/or forms deposits. The link to the tests of various oils is in the first post.
     
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  14. Grit

    Grit Senior Member

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    What oil would you guestimate that will minimize clog, withstand high temp w/o leaving too much blow by?
     
  15. nick31

    nick31 Member

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    Honestly I don't know. It seems that all mineral oils are doing well after the heat test and a lot of synthetic oils fail it. The author of the method recommends a few oils but only 1 "approved" is available in the USA (liqui moly molygen).
    Also after reading more it seems I'm totally wrong about the importance of the noack test. It doesn't matter really. Good oil should not polymerize and form deposits, that's the main idea.
     
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  16. Grit

    Grit Senior Member

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    Thanks for your reply. My current engine oil is red line and hoping it fits the bill you had mentioned about polymerizing & deposits. Just wondering if that oil will be the long term oil to use.
     
  17. nick31

    nick31 Member

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    You can test your oil yourself using a spoon and a butane lighter. Sounds silly, but it seems to give some insight.

    Example
     
  18. hotelprisoner

    hotelprisoner Member

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    Never tried it but looking at the AMSOIL Signature Series 0w20. Anyone have any issues using it or get a funky UOA with it?

    The specs look interesting, specifically, the TEOST which seems like a quality along the lines of our ideal fluid to prevent coking the piston rings or drain hole environment.

    Unfortunately I couldn’t locate an equivalent result for the M1 EP 0W20 currently in the crankcase.
     
  19. nick31

    nick31 Member

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    Take a look here. Amsoil was tested and probably 0w20 has the same base oil.
    M1 doesn't do that great when tested.
     
  20. hotelprisoner

    hotelprisoner Member

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    I had previously thought the M1 was good, but now... A lot of reading of others’ opinions on oil is very subjective. I read elsewhere the no-go dinner topics are politics, religion and engine oil.

    Testing and data is a better approach and I’m willing to go off the beaten path to find an alternative oil to get ahead of this problem so long as I don’t create a new problem. Toyota is not going to help us so we have to adapt to the situation at hand or face coked rings, blown head gaskets etc.
     
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