Why would you run 0w-20 in a desert (hot) climate? (yet another oil thread)

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Chabelo, Apr 28, 2015.

  1. Chabelo

    Chabelo Junior Member

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    I have a case of mobile 5w-30 oil, i used that for my first DIY oil change on my PIP but I noticed the manual states "if 0w-20 not available, you can use 5w-30 but make sure you use 0w-20 the next time". What is it about the prius engines that toyota wants you to use such a thin oil? I can understand arctic temps requiring such low viscosity, but California? Seems counter intuitive but there must be a reason...
     
  2. ITgem679

    ITgem679 Junior Member

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    This is really interesting. I wasn't aware of such a light oil being used. I have always used a heavier weight oil in the summer, lighter weight in the winter - but that was when we lived in Arizona. In CA, where I reside now, the year around temps are pretty consistent so I would figure 5w 30 would be OK year 'round. However, I digress...From what I understand this lighterweight oil actually assists with fuel savings. Since it is the weight of the oil we are addressing:

    According to Why 0W-20 Synthetic Oil? (Explanation inside) - Toyota 4Runner Forum - Largest 4Runner Forum,

    "Because 0W-20 flows so well at cold temperatures, it lubricates parts faster during cold starts. Most engine wear occurs during the first couple of minutes after a cold start and fast flowing oil protects sooner; it also allows the engine to crank faster so it can start more quickly. These are real benefits on a cold Canadian winter morning.
    Another benefit of 0W20 is reduced internal engine friction, which improves fuel economy in the range of 0.5 to two per cent. This may not seem like much, but improving fuel economy is done in small steps. Every little bit helps and it could save you several hundreds of dollars in fuel costs over the life of the vehicle.
    Some of the fuel economy savings result from less power needed to drive the oil pump in the engine – the lighter viscosity oil just flows more easily. Internal engine changes over the years have been made to accommodate thinner viscosity oils. Different oil ring design and roller contact points for the valvetrain reduce a lot of sliding friction.
    Engine oil prevents wear by separating moving parts from each other. The oil forms a boundary layer so the parts don’t touch but high spots on the parts can penetrate the oil film and cause wear. More precise tolerances and more accurate machining processes for engine parts help the thinner viscosity oil protect the parts.0W-20 oil provides the best lubrication under all temperature conditions, reduces engine combustion chamber deposits, reduces vehicle emissions and improves fuel economy. That’s a lot to ask of engine oil, but 0W-20 synthetic is up to the task. "

    I know Toyota trucks are not a Prius, but however Toyota seems to recommend the same oil for their vehicles across the board.
     
    #2 ITgem679, Apr 28, 2015
    Last edited: Apr 28, 2015
  3. kbeck

    kbeck Active Member

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    Well, I'm a-gonna make my argument. Asbestos suit, check. Helmet, check.

    When one reads about 0W-20 doing a great job in cold weather, it strikes me that "cold weather" might be pushing it a bit.

    When the engine is operating temperatures in the crankcase, cylinders, and other such places where oil is required to splash will be somewhere north of 100C; possibly 120C on the cylinder walls, cooler elsewhere. (Water cooling keeps the iron colder than what one would get with an air-cooled engine.

    Now, consider three cases: A cold day with snow all over; -10C. A "normal" day, 25C; and a hot day, perhaps 35C. I posit that, compared to operating temperatures, one is more-or-less comparing apples and oranges. All of these three temperatures are a lot less than normal operating temperatures of the engine.

    Hence: "Cold" could simply be taken as an engine that hasn't warmed up yet. Although I don't like the word, "warmed". That engine isn't just warmed up; it's sizzled up. (That is: Apply hand. Then, remove hand with 2nd degree burns.)

    Therefore: When Toyota calls for 0W-20 for better performance/less wear on a "cold" engine, that includes a Prius that's being started for the first time on a day in the dead of summer. it may be warm out there with the sun blasting away; but it's nothing like the interior of a running engine, and "cold" can simply mean 70C from the warmed-up/sizzled-up state.

    So, my argument is to stay away from 5W-20; you'll get more wear on a cold engine, even when the outside temperatures are Up There.

    Comments?

    KBeck
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The reason is to maximize fuel economy, a thinner oil is easier to move through the lubricating system, less friction, etc. Toyota says that their current engine line is designed to thrive on 0W-20 full synthetic oil.

    Older engines, like the 1NZ-FXE found in Classic and 2G Prius, retain the 5W-30 viscosity recommendation in North America. If 0W-20 is used, fuel economy may improve as much as 5% in cold weather, but there is some likelihood of additional engine oil consumption in hotter climates.
     
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  5. CR94

    CR94 Senior Member

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    It's difficult to believe 5W-20 at 35°C is so high in viscosity that it causes undue cold-start wear, but 0W-20 at -10°C isn't. There should be little difference between them at operating temperature, assuming equal oil quality in other respects.
     
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  6. wjtracy

    wjtracy Senior Member

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    every once in a while someone posts this confusing chart here (see PDF). It does show only 0W-20 TGMO is spec'ed for 2011+ Prii but it only goes up to 2012. TGMO is Toyota Genuine Motor Oil. For Gen2 (where 0W-20 is strangely shown which seems to contradict owners manual) someone wrote to Toyota to ask about it, and posted the reply here.

    But sounds like Toyota really wants the low temp low visc (0W) for Gen3. I don't know exactly why, but I am under the (possibly mistaken) impression that Gen2 engine oils tended to build up more gasoline in the oil (couple percent), so sort of a diluent, but Gen3's maybe not as much gasoline in the used oil...so any low temp fluidity needs to come from the oil. Also highly rated A5/B5 5W-30 oils get that rating by holding their viscosity (less break down to lower viscosity).

    When people have posted TGMO specs, the low temp viscosity of the Toyota oils seem superior to other brands. So most other 0w-20 motor oils are not going to be as good as Toyota's, and conceivably a non-Toyota 5W-30 looks too heavy to Toyota in the cold car, even if cold is 25C some nights. There is 0W-30 but not sure if Toyota makes that.
     

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    #6 wjtracy, Apr 29, 2015
    Last edited: Apr 29, 2015
  7. qdllc

    qdllc Senior Member

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    I see another angle.

    The Prius motor isn't ON all the time...even after it warms up. I'd wager that short of constant highway driving, the Prius ICE isn't anywhere near the heat stress of a standard ICE vehicle that runs all the time and needs constant venting of the excess heat.

    So, in a way, the Prius motor is always on the "cool" side of the operating temperature range. Oil might be warmed up for viscosity concerns at cold start, but it's not "hot" either.
     
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  8. DoubleDAZ

    DoubleDAZ Senior Member

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    And isn't it true that even though the ICE isn't actually "running" all the time, the parts are still moving at low RPMs at times? Wouldn't the lighter weight oil be better under these conditions?
     
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  9. qdllc

    qdllc Senior Member

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    Unless you go over 45 mph, the ICE shuts down when not needed or enough input from the accelerator engages the ICE for additional torque or keeps it in "standby" mode.
     
  10. Mendel Leisk

    Mendel Leisk Senior Member

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    I usually have engine coolant temp showing on ScanGauge, and in around town driving I see temps typically around 50~80C, lower than the typical 90C you'll see on highway.
     
  11. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Many oil threads.
    Same answer.

    RTFM.

    FWIW, I don't think that the 5w30 will hurt the car in any measurable way, and If it costs you as much as 1MPG I'd still use it for three oil changes (@ 5,000 per oil change) just to get it out of the garage.
    Or?
    You can use it for bar lube if you have a chain saw.
    Or give it to a friend with a GM.

    The point is that it's really not going to matter all that much.

    Good Luck!
     
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  12. FuelMiser

    FuelMiser Senior Member

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    I would just go with the Manufacturer's recommendations, 0W-20 Full Synthetic for 10,000 miles. Modern synthetic oil is not the same as the "dino" oil we grew up with. Rules of thumb from the old days just do not apply. Keep it simple.
     
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  13. Mendel Leisk

    Mendel Leisk Senior Member

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    Toyota spec's different oil weights around the world, and different distance/time change intervals. It's not completely objective: marketing, mpg goals, consumer attitude, all play a role.
     
  14. wjtracy

    wjtracy Senior Member

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    If you look at Toyota's TGMO chart I posted above/below, Prius is just one of many newer 2011+ Toyota vehicles that is shown for only 0W-20. It definitely appears that Toyota is moving to engine designs/clearances for which they want the 0W low temp low viscosity, even non hybrids I am thinking. I don't personally own a 2011+ Toyota, but seems like we are stuck with 0W. I might go 50/50 if I was trying to blend off.

    Toyota Motor Oils.jpg
     
    #14 wjtracy, Apr 29, 2015
    Last edited: Apr 29, 2015
  15. CR94

    CR94 Senior Member

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    True, and they also have to consider differing physical and regulatory climates, among other other factors. Oil that's approved for an engine in one country is probably fine in an identical engine within the same temperature range in another country.
     
  16. Former Member 68813

    Former Member 68813 Senior Member

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    1. this is canada toyota, not for USA consumption.

    2. there are so many mistakes, it should not be seriously considered.

    3. how do we know it's not fake? i never saw it hosted on an official toyota websites.
     
  17. wjtracy

    wjtracy Senior Member

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    You are correct: I do not know where it comes from (except others posted it on PriusChat and I saved it).
    But specifically what do you see wrong with it? It correctly shows 5W-30 for Gen2 and 0W-20 for Gen3.
    The one thing I see potentially wrong (for USA) is that they say 2010 MY Prius is 5W- or 0W-20, but i do not know you tell me what the 2010 manual says. Could be for Canada I guess that's possible.
     
  18. Patrick Wong

    Patrick Wong DIY Enthusiast

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    It incorrectly shows 5W-20 for Classic; and 5W-20 and 0W-20 for G2. I have not seen an official TMS USA document with that recommendation.
     
  19. wjtracy

    wjtracy Senior Member

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    Right we have that in a letter from Toyota USA but not official. This chart is not consistent with any specific vehicle MY as far as I know all cars have a single grade stamped on the oil cap, so this is more the range. In any case, I was saying the chart implies to me 0W-20 is the new requirement...no range anymore. Any exceptions in USA? Canada? I'd be curious to hear if Aussie requirement is also 0W-20.
     
  20. Mendel Leisk

    Mendel Leisk Senior Member

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    I'd be 100% more interested in someone running a heavier oil than spec, and reporting mpg impact. Say a 3rd gen running 5W-20.
     
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