Oil viscosity impact on fuel economy

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by harrysprius, Jun 19, 2017 at 9:14 AM.

  1. harrysprius

    harrysprius Junior Member

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    I did the first oil change on the 2010 Toyota Prius I recently purchased, and I used the Mobil 1 0W-20 Hybrid Formulation. I have noticed over the last couple days that the mileage is up about 2 MPG. Has anyone seen any differences like that? I have no clue what was in it, any input?
     
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  2. wjtracy

    wjtracy Senior Member

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    The question would be what was in there before?...but generally speaking YMMV (your mileage may vary) depending on many variables so it is usually extremely difficult to pinpoint a definitive cause and effect. In the summer we might expect little difference. In the winter maybe a thinner lube might show an effect.
     
  3. harrysprius

    harrysprius Junior Member

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    I wish I knew what was in it. There was no sticker and the oil maintenance light came on. The oil looked clear and clean but I just figured better safe than sorry. I did set the reminder to 10 K this time. It was on 5.
     
  4. DonDNH

    DonDNH Senior Member

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    Suggest you check the oil level in a couple of hundred miles; it might have had a higher viscosity oil in it to slow the burning of oil.
     
  5. harrysprius

    harrysprius Junior Member

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    Good point. I've been checking every fill up for the last couple thousand miles and hadn't seen and loss. Hopefully it stays the same. Thanks DonDNH.
     
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  6. StarCaller

    StarCaller Active Member

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    how you did that????
     
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  7. harrysprius

    harrysprius Junior Member

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    Under maintenance, you can set your reminders for oil and filter. and just about anything actually. Rotations, brakes, transmission service, spark plugs, wipers.....
    I'll try and screen shot it later. I'm stuck in the office for now.
     
  8. Mendel Leisk

    Mendel Leisk Lapsed Cargo Cultist

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    The big unknown is what was in there. Any way to find out? Maybe 5W30?
     
  9. harrysprius

    harrysprius Junior Member

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    No clue. Just bought it couple weeks ago.
     
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  10. friendly_jacek

    friendly_jacek Senior Member

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    looks like he has model V with more functions?
     
  11. 4md

    4md New Member

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    That intervals are programmable on the sat nav units, not the interval, displayed on the MFD, that can be reset using the miles/km button.
     
  12. harrysprius

    harrysprius Junior Member

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    It was on the MFD, sorry if that was confusing., but 4md is correct. It is a V as well.
     
  13. DrTrivia

    DrTrivia Junior Member

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    The Mobil 1 Advanced Fuel/Hybrid oil lists on the cover that it increases MPG. However, on the back it lists that the increase in MPG is something like 0.2%-2% based on tests. This seems like almost nothing, but technically 2% (maximum) could mean something to prius owners. Unfortunately there is additional fine print. It says (in more confusing wording) that this increase in MPG was achieved when switching to 0W-20 from a higher viscosity. So basically the oil will increase you MPG, by as little as 0.2%, but only if you were using the wrong oil in your car to begin with. Like the "annual protection" Mobil 1, this is a scam oil targeted at people who don't read the fine print. Aside from the deceptive advertising, I don't think it's any better or worse than any other synthetic 0W-20 oil on the market.
     
  14. orenji

    orenji Senior Member

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    My two cents, use 0W-30 weight Mobil One oil, Toyota Filter always and switch back to 5,000 mile intervals if you want to assure longevity of the ICE.
     
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  15. Mendel Leisk

    Mendel Leisk Lapsed Cargo Cultist

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    I do most of that, except 0W20 Toyota oil. I follow Canadian 6 months or 8000 km (roughly 5000 miles) except: 6 mo usually arrives well before 8000 km, more like 5000. If that.
     
  16. Rebound

    Rebound Senior Member

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    Using a lower viscosity motor oil will increase gas mileage. The engine has less resistance to cut through as it spins 2,000 to 3,000 times per minute. Problem is, that thinner oil doesn't stick to the engine parts quite as well, so the engine may not be as well protected.
     
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  17. David Beale

    David Beale Senior Member

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    The "correct oil viscosity" is not just 0W20. In the US and Canada yes, but that is set by govt. requirements that fuel economy be maximized. In more reasonable places the viscosity is specified by Toyota based on ambient temps. Check out the recommendations in Australia, for example.

    I still think the 0W20 is responsible for starting the engine on the path to oil consumption. It's a long and winding road (to quote a song), but very suspicious.
     
  18. ETP

    ETP Ancient sloth foot

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    After owning 10 hybrids the answer is yes.
    Oil viscosity greatly affects MPG in a hybrid like the Prius. Some cars require 10W30 or 5W30 per manual. The Prius requires 0W20.
    The factory puts in 0W15 so sometimes folks notice great mileage when they drive off the lot.

    Tire pressure is also in the top 3 on MPG. The more pressure the better the MPG.

    Then driving habits!!!!!!!! An experienced hybrid driver will get better MPG than a normal person gunning the throttle in traffic to get that extra car length. Speed kills MPG.

    Road rage is a great sign you have submitted to the Force.
     
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  19. ETP

    ETP Ancient sloth foot

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    That is the quandary. Spot on! But if you get over 100K out of a Prius that is outstanding. I would use 0W30 or 5W20 in very hot climates (SW in the Summer). 0W40 is too heavy for a Prius.
     
  20. Rebound

    Rebound Senior Member

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    I've run 0W20 for over 100K miles and I still have a few jugs of it left. After that I'll switch to something heavier, like Mobil 1 5W30 or 10W30
     
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