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OW20 oil in hot climate

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by E-GINO, Apr 29, 2013.

  1. E-GINO

    E-GINO Active Member

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    Since the first ICE oil replacement at 15000 Km, I've been double checking that maintenance technicians shall put the recommended type of lubricant in the engine, i.e. the 0W20 grade (initially Toyota branded, now Castrol).
    Every time I had to fight hard with the Toyota head of mechanics, since he reckon that in hot climate the 5W30 grade lubricant is more recommendable (and cheaper BTW).
    Now, since every summer I make a 2500 m travel with my MY 2010 Prius loaded with 4 pax and a luggage box on the roof ,at highway speed ( 130 km/h in my country), being my next oil change not too far, I am wondering what is - in general - the oil change habit of those of you who live in hot climate... do you ask for 0W20, or prefer the 5W30 one?
     
  2. spiderman

    spiderman wretched

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    Perhaps a 0W-30 would be more suitable? Probably the best thing to do is have an oil analysis done to see how the 0W-20 is holding up under those conditions. Do you have a place that will do that in Italy?
     
  3. Former Member 68813

    Former Member 68813 Senior Member

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    Since it's only 2500 meters, I would not worry about 0W20.
     
  4. phoenixgreg

    phoenixgreg Senior member

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    0W20 is the OEM recommendation no matter the climate. It gets to 117+ here Fahrenheit and I've always used 0W20 synthetic (good for 10,000 miles). Expensive but worth it.
     
  5. xs650

    xs650 Senior Member

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    For sustained speeds of 130km/h in hot weather with a luggage box on the roof, either 0W-30 or 5W-30 synthetic would be a good choice. You most likely wouldn't have any problems with 0W-20 but 0W-20 would be closer to having a problem than xW-30 under those condition.
     
  6. E-GINO

    E-GINO Active Member

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    I agree, the Manufacturer designed the engine and should know which kind of lubricant is better for the engine.
    I wonder why mechanics, that attended OEM maintenance training courses,I suppose, keep recommending 5W30 oil, though.
    However, during such 2500 miles trips I've been monitoring HSD parameters with SCG, and the only one parameter that worried me a little bit was the MG2 temperature, which sometimes reached 105 C, during steep high speed climb. Probably, this is the reason for which Toyota does not allow the towing with the Prius, the MGs cooling system seems not too much efficient.
     
  7. xs650

    xs650 Senior Member

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    Yes, the the manufacturers do know. Unfortunately, we as consumers have no way of knowing what the Toyota powertrain engineers would use in their own cars under our individual driving conditions. Do you really think one grade of oil is optimal for all conditions?
     
  8. E-GINO

    E-GINO Active Member

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    Honestly, I do not know. What is indubitable is that technology of both engines material and design, and lubricants specification, had improved greatly in the last 20 years; IMO question is whether or not what the OEM states in the User’ manual has to be considered binding. They say "do not tow", then I do not tow; they write "the lubricant has to be changed every 15.000 km", then I follow scrupulously the directive (although my previous 2002 diesel car had the oil service prescribed every 50.000 km; and diesel engines make the lubricant a lot dirtier than petrol engines).
    If Toyota says "use 0W20 oil", without adding something like "... except with heavy loads in hot climate use", do I have the competence to decide differently? I rephrase: do Toyota maintenance technicians have the competence to decide differently?
    I have also been thinking... please correct me if I am wrong: in the HSD system, by design ICE works constantly full loaded; then, a critical aspect for an internal combustion engine, as the lubrication in hot climate under heavy loads, had to be carefully evaluated by Toyota engineers....
     
  9. Bill Norton

    Bill Norton Senior Member

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    Gino,
    No, the ICE puts out the power required to propel the car. This is no different than non-hybrids.
    What the HSD does is allow the ICE to make the required power at the most fuel efficient RPM and Throttle position.
    I have an Engine Gauge display and can watch the ICE do its thing.

    I read here that the Australian Prius manual calls for thicker oil.
    I think the CAFE fuel economy standards make the manufacturers want to use the thinnest possible oil.
    It may not be the best for long term engine life. Especially when it is really hot out and you are flogging the car up the mountains.

    And why are 5k, 10k mile oil changes such a fixed number?
    I think it is the condition of the oil that matters.

    I just changed mine at 7k miles, 0-20W Mobil 1, and I wish I had changed it sooner.
    It stunk and was darker than expected. I sent it in for analysis. I'll be posting the results.
    This oil went through the winter months, which are the hardest on oil. It doesn't get up to temp often enough to evaporate moisture.

    This time I used Mobil 1 Extended Performance 5-20W and will try to go the 15k miles claimed for this oil.
    The summer months are easiest on oil and I plan on a few Road Trips !!
    I'll post analysis of this oil also. Later, much later. If it tests well, this could mean 50% less oil changes in the future !
     
  10. Former Member 68813

    Former Member 68813 Senior Member

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    The only problem is you didn't monitor oil temp or oil pressure and only those would give you the answers you are looking for.
     
  11. Former Member 68813

    Former Member 68813 Senior Member

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    Actually this is almost exactly what Toyota says in US manuals.
     
  12. tumbleweed

    tumbleweed Senior Member

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    Here is a copy of the relevant pages from the Gen 3 Australian Owner's manual, same engine we have. Make of it what you wish. It leads me to believe CAFE Standards, coupled with the EPA rule that the oil viscosity used for mileage tests be the oil viscosity required for use by the customer, are the driving factor for 0W20 oil requirements. However the engine seems to tolerate 0W20 because most of us have been using it for years now with no apparent problems.
     

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  13. edthefox5

    edthefox5 Senior Member

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  14. Maroon

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    I've been wondering about going to 0W30 in the summer. My commute is mostly highway, but I'm not a hypermiler and let the cruise control do its thing, so on some hills the HSI goes into the "power" section for a while. Anyway to monitor oil pressure on the Torque app to see if maybe the 0w20 is thinning out?
     
  15. telmo744

    telmo744 HSD fanatic

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    Thank you. What date or which MY was this manual?
     
  16. Bill Norton

    Bill Norton Senior Member

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    To me, when this Prius manual says:
    "An oil with a higher viscosity may be better suited if the vehicle is operated at high speeds, or under extreme conditions" , that sounds like any Interstate Highway in America.
    And then add really high summer temperatures while climbing the mountains....

    It doesn't matter what model year this manual is for.

    If you wait until an oil related issue becomes apparent, you now have an engine that has a clatter.
     
  17. E-GINO

    E-GINO Active Member

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    Well, I monitored ICE and inverter coolant temperature, no issues with them. But you are right, oil temperature is more significant, I will set it in one of my Scangauges - there is no Xgauge for oil pressure, as far as I know.
    A similar sentence is written in the European Prius manual, I did not notice it before because is written in the following page.
    However, at 130 km/h cruise control GPS speed , ICE spins at 2850 RPM, even with the luggage box on the roof. I would not say that this is a high rotation speed for a gasoline engine... what changes dramatically between the two conditions is the fuel flow, which at such speed, no climb, dry surface, 30 C OAT, A/C on, 4 pax, is around 5,8 l/100 km in normal configuration, and around 7 l/100 km with the additional drag due to the luggage box.
    In general, during climb at highway speed ICE RPM may increases up to 4800 RPM, again a fairly limited rotation speed for a modern, twin OHC gasoline engine. But I don't like the noise that ICE emits above 4000 RPM, so when possible I relax the speed as much as necessary to contain the ICE RPM under 4000 RPM.

    Regarding my Prius ICE health, well I believe it is pretty good, the car has just 53000 km on its shoulders, and the lubricant consumptions are the same as when the car was new: zero, never had the need to refill a bit. All in all, the 0W20 lubricant costs here around 20 € per liter, like a bottle of good wine... it is supposed to be a good oil. Nevertheless, at the next oil change I will consider some boron nitride additive, like Liquimoly or better.

    Post scriptum: during business trips in the States, I have driven several times a rented Prius on the I-95, at 70 mph GPS speed with cruise control set (tipically, from Miami to Orlando and viceversa). Never had the sensation of "extreme conditions" though...
     
  18. tumbleweed

    tumbleweed Senior Member

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    It was originally posted by one of our Australian PC members, I can't find the topic right now but as I recall his car was definitely a Gen3 and I think it was a 2010.
     
  19. Former Member 68813

    Former Member 68813 Senior Member

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    First, it initially sounded like you asked a question, but in reality you wanted to hear a confirmation of your believes.

    Second, oils additives are not needed without specific engine problems. Modern oils do contain boron in balance to other AW/FM agents. If you add more of one agent, the whole will not be necessarily better.
     
  20. Former Member 68813

    Former Member 68813 Senior Member

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    Yes, to the 3rd gen. The 2nd gen in Australia is this: http://i35.tinypic.com/29xyx3c.png (sorry, for some reason I can't embed images in PC anymore).

    Interestingly, 0W20 was OK in 2nd gen in UK.