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0w-20 and 0w-16, way too thin. 5w-20 or 5w-30 instead?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Priipriii, Sep 16, 2023.

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  1. Priipriii

    Priipriii Member

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    This might be borderline a conspiracy theory, but do you think Toyota purposely wants us to use thinner oil to boost their 'mpg' rating and for planned obsolescence?

    Its not a mystery that thicker oils help protect engines better and last longer in the long run due to oil having a higher amount of lubrication for metal on metal contact. Sure you might lose 2 or 3 extra mpg from the resistance that a thicker oil might cause, but that comes at the cost of your engine parts lasting longer. Ive notice over the years, the 4th gen priuses which use the same 1.8L engine as 3rd now recommend 0w-16 instead of 0w-20. What do you guys think of that and why do you think that is?

    Also for very high mile priuses, would it be wise to put 5w-30? Thinking of doing the jump
     
  2. Mendel Leisk

    Mendel Leisk Luddite

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    5W30 was the gen 2 spec. As far as I know they plunked the same engine in the Prius c, and there said use 0W20. Does make you wonder.
     
  3. PriusCamper

    PriusCamper Senior Member

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    However, because its a hybrid car you aren't solely dependent on the gas engine and a Prius with 300K miles will only have less than 200K miles of engine wear.

    That being said, gen3 engines are a huge fail in longevity when it comes blown head gaskets and piston rings that burn oil... So maybe a thicker oil might help. But also maybe a thicker oil will run hotter and these Gen3 engines seem to blow headgaskets in part due to running too hot.

    So my input is what they said in that old STP motor oil ad on tv in the 80's: "Motor oil is motor oil."
     
  4. ColoradoBoo

    ColoradoBoo Senior Member

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    Not at all...our modern engines are designed to work well with lighter oil.

    If you are still skeptical, watch this scientific lab test....results will help you sleep at night!! (And never put a different oil weight that is on the fill cap...it can void your factory warranty.)

     
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  5. BiomedO1

    BiomedO1 Senior Member

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    I don't think it's a conspiracy, but the thinner oil does make it easier for them to pass CAFE standards and improve mileage.

    I don't live in the snow belt and if any landed - it'll be gone by 10AM. When my 2012 Prius C started burning a quart every 10K miles, I switched to 5w20. Oil burn slowed to 1/4 to 1/2 quart every 10K miles. Couldn't do any long term testing, since an uninsured motorist totaled it out @ 93K miles. I think I started putting in 5w20 around 70K-80K miles.

    As for thicker oil makes an engine last longer, I really can't be sure of that. Testing is usually done on race car engines, proof of concept. They get rebuilt after every race. While they do measure internal wear, in the thousandth of an inch, what is the accuracy and fudge factor? Even race cars has gone to thinner oils - then again, the engines gets rebuilt after every race. The tolerances in these modern engines are getting very tight, because the tools we use to build these engines are getting better. Will thicker oil flow into those tighter spaces and move across as the engineers predicted or will it burn and seize the bearing. I don't know - I'm only willing to make small minor tweaks to specifications. This mitigates the damage, I may cause by not follow specifications.

    That's my 2 cents on the subject...
     
  6. Tombukt2

    Tombukt2 Senior Member

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    They've done a lot of work on the one NZ over the years got a rally version of it and everything making big horsepower so I'm sure they've tweaked the internals to run the 020 the 016 in the super cold so on and so forth The one NZ keeps getting tweaked.
     
  7. PriusII&C

    PriusII&C Active Member

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    That's very early and severe. Do you know what might have caused that to happen?
     
  8. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    0W-20 had close to zero availability when the second generation Prius arrived.

    Much easier to buy the stuff by 2012, when the c arrived.

    Not that hard to work out.

    Not borderline. Over the line.

    If there was a problem with the performance of modern 0W oils, they would have been chased off the market ten years ago and we would all still be using thicker stuff.
     
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  9. BiomedO1

    BiomedO1 Senior Member

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    @PriusII&C That's NOT severe. Dealers won't warranty a motor replacement unless it burns more than a quart every thousand miles. They (Dealers) claim that's NORMAL.:(:oops::eek:

    So, if we do the math. The first oil change is 10K, but you've already put 10 quarts of oil into it. Does it really need an oil change????:p:cool::D:rolleyes::LOL::love::ROFLMAO::whistle:(n)

    I had a friend with a new Subaru, only 4K miles doing that. But knowing him, didn't properly break-in the motor. Hey, I've got a Subaru, lets race.:eek::cry::sleep:
     
    #9 BiomedO1, Sep 16, 2023
    Last edited: Sep 16, 2023
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  10. Tim Jones

    Tim Jones Senior Member

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    I have ran 20w50....plus 10w40 and 10w30
    Even ran 10w40 motor oil in the trani.
    I was under the impression that the C had a different ECE..... I love toy's but 3rd Gen Prius bad idea for presumed longevity.
     
  11. Tombukt2

    Tombukt2 Senior Member

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    And that's interesting because when I used to build engine internals the rods and mains got prelube. But I would put the bores up pretty much dry. After honing and cleaning a light wipe with marvel mystery oil or something was about it. Fit the rings fit the compressor push them in the bore usually with the top of my hand rarely the wooden end of the hammer handle when you start that engine up the ring seat in about 45 seconds no kidding.we used to use Deves swedish rings.
     
  12. rjparker

    rjparker Tu Humilde Sirviente

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    0w8 in tbe new turbo hybrid max
     
  13. taxidriver50005

    taxidriver50005 Active Member

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    Running 5w/30 in my 370,000 mile prius... Yes head gasket has failed at 350,000 but when taken apart garage was well impressed by how little wear there was on engine.

    Posted via the PriusChat mobile app.
     
  14. Priipriii

    Priipriii Member

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    What was your average gas mileage
     
  15. taxidriver50005

    taxidriver50005 Active Member

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    62mpg...in the UK... Changing to heaver oil made no difference... Oddly enough since head gasket was done I've switched back to 0w20 and would you believe it... There is still no difference... When my stock of 0w20 runs out I'm straight back on 5w30.
    Posted via the PriusChat mobile app.
     
  16. Tim Jones

    Tim Jones Senior Member

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    Good Idea.
    I really did have Super Tech 10w40 SYNTHETIC
    AND Lucas Oil stabilizer in the trani.
     
  17. Priski

    Priski Junior Member

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    Man what are the secrets to making it to 370K? Almost at 200
     
  18. Tim Jones

    Tim Jones Senior Member

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    200,000 is when the real pain begins.
     
  19. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Put the miles on fast before the car realizes it is old.
     
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  20. Siward

    Siward Active Member

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    I dump in 0w20 in the winter and 5w20 in the summer these days. It is all about viscosity vs temperature.