My experience using 5W-40 instead of 0W-20

Discussion in 'Gen 3 Prius Fuel Economy' started by Anas Almustafa, May 18, 2014.

  1. Anas Almustafa

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    hi all,

    I use to get 48 mpg average on my 2010 Prius using 0w20 oil. I switched to Lexus 5W-40 fully synthetic oil as the local toyota dealer in Jordan suggested and now after 467 km i filled up the tank with 26.2 liters which is almost 41 mpg, that's a (( 7 mpg drop)).

    The gas pedal is a bit harder to press with the new oil.

    I recommend sticking with the suggested oil grade 0W-20

    Currently planning to switch back to 0W20 and see if i get my 7 mpg's back.

    *************((update 27 June 2014))**************
    I did notice a sluggish response when i first switched to 5w40 but i decided to test it for a while.

    I kept the 5W40 and after almost 1000 km i got back to 47 mpgs this might be because the oil got thinner by time.

    (((( I think the 7 mpg drop was due to the 12 volt battery full cpu reset which happens to be at the same day i used the 5w40 engine oil )))).

    ((see my fuelly notes for details))

    I'll be switching to 0W20 on the next oil change and report if there is any dramatic difference

    *************((update 20 Aug 2014))**************
    I have used 5W20 for almost 8000 km and got an avarage of 40 miles per gallon

    *************((update 10 Oct 2014))**************

    I have used dealer recommended oil Lexus 5W40 fully synthetic here in jordan and got back to 47 mpg

    ******************************* Final Advice ****************************
    STICK WITH THE RECOMMENDED OIL FROM YOUR LOCAL DEALER

    I JUST HAD TO TRY FOR MYSELF :) I hope this helped
     
    #1 Anas Almustafa, May 18, 2014
    Last edited: Jan 1, 2016
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  2. JC91006

    JC91006 Senior Member

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    Were you having problems with 0w-20? Wondering why you switched. There shouldn't be a suggestion from dealers to go away from what Toyota specifies unless there is a problem

    SM-N900P ?
     
  3. Anas Almustafa

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    The dealership in jordan always suggested Lexus 5W-40 fully synthetic oil and currently doing so for all prius 3 gen users. I was using 0W-20 valvoline fully synthetic oil from outside store not the dealership. I switched because I thought that 5w40 is better for an engine with 140k km on it.
     
  4. hill

    hill High Fiber Member

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    Your imagination got the best of you. The pedal is electronic - no direct mechanical connection between it & the fuel injection system. The physics between MPG drop & thicker oil is pretty straight forward. Just like MPG drop in rain - you're pushing through thicker atmosphere - and the ICE is pushing thru thicker lube ... both rob the Prius of its normal high efficiency.
    .
     
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  5. Anas Almustafa

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    The engine response vs pedal press ratio is a bit stiffer you can tell the difference when driving the same car before and after the oil change .
     
  6. hill

    hill High Fiber Member

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    Try using a tensionometer next time said experiment is in order ... it'll remove all subjectivity, and the before & after results will coincide - guaranteed
    :)
    .
     
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  7. Mendel Leisk

    Mendel Leisk Underfoot

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    It could seem like the pedal is stiffer, since you need to push a little further to get the same reaction. 7 mpg further...

    I wonder how 5W20 would compare to 0W20, by comparison.
     
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  8. telmo744

    telmo744 HSD fanatic

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    Some portuguese Prius owners have tried 10W40 and 5W30 with no much difference. I would try an average of tanks...extending observation span.
     
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  9. mtbiker53

    mtbiker53 Junior Member

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  10. Anas Almustafa

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    hahaha i am glad you found that funny steve ;)
     
  11. GrumpyCabbie

    GrumpyCabbie Senior Member

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    Reflects what I reported years ago (not a dig at you).

    The car seems much more hesitant on the thicker oil and the transition from electric to engine isn't smooth. I also couldn't get a journey average over 59 mpg UK however hard I tried on 5w30.

    Now you see why it's worth paying a little extra and using the oil that is recommended for the car.
     
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  12. Anas Almustafa

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    yes this is whats happening i have to push the pedal more to get the same response i was getting before changing the oil to 5w40
     
  13. GrumpyCabbie

    GrumpyCabbie Senior Member

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    You probably have to accelerate harder to get the engine to turn against the thicker oil. I bet the car wasn't as fast on hills either?
     
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  14. Anas Almustafa

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    I really didn't try it on up hill roads nor did i push it too hard. I was accelerating slowly most of the time.
     
    #14 Anas Almustafa, May 20, 2014
    Last edited: Jul 6, 2014
  15. Anas Almustafa

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    exactly , thank you for clarifying that
     
  16. GasperG

    GasperG Senior Member

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    When I bought my car used the seller (Toyota dealer) did a "cheap" service and used BMW longlife 5W40, I was trying really hard to get 4.4 l/100 km on my daily commute, I changed it before winter with Mobil1 0W20 and was disappointed because the winter took it's toll, but when the spring came I was hitting 4,2-4,3 l/100 km. You can see several tank fill ups from 2011 in my signature.

    I would call it at least 3-4% (0W20 vs 5W40) lower consumption in warm weather, god knows what would happen in winter. Difference in comparison to 5W30 would be a lot less, probably 1-2%.
     
  17. Former Member 68813

    Former Member 68813 Senior Member

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    It all depends on driving style. There would be little difference with fast hwy driving, but huge difference in short trip driving with oil not up to the regular temps. Different oils for different duties. Wait, I forgot, we have only one CAFE oil in USA.
     
  18. abudraih

    abudraih Junior Member

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    Hi Anas

    Nice to see another Jordanian Prius owner who is suffering from the local dealer

    FYI, now a days the available oil on the Toyota dealer side is the 5w 30, not even the dealer but all the other garages here, and they are trying to convince you that they have more knowledge that the manual, they says that our USA market Prius is designed to use the 0w 20 oil but the climate for Jordan is better with the 5w 30 , and if you want to make sure just read a prius manual of a Jordanian or middle east prius

    i am really confused , i have a 2013 prius and i dont know to change to 5w 30 or just order 0w 20 online ?//
     
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  19. Easy Rider

    Easy Rider Active Member

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    You are worrying WAY too much.
    Just use what the local dealers use for everybody else and be happy. :)
     
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  20. GrumpyCabbie

    GrumpyCabbie Senior Member

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    Thinking about it they might have a point.

    In the UK we're recommended to use 0w20 oil and our temperature ranges from -10c to 30c at the extremes. If your temp is 15c-50c then the thicker 5w30 oil might be the one to have.

    I can't imagine fuel consumption is an issue in Jordan either :)
     
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