Any appreciable gain with 0w-20 oil?

Discussion in 'Gen 2 Prius Fuel Economy' started by PriusGuy32, Dec 13, 2012.

  1. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

    Joined:
    Sep 10, 2012
    1,313
    423
    0
    Location:
    Harrison Township, Michigan
    Vehicle:
    2013 Chevy Volt
    Model:
    N/A
    I have a Gen2 2007 that I bought in September. I changed the oil myself (Im a major DIY'er) and used Mobil 1 5w-30. At the time I wanted to put in 0w-20 Mobil 1 but wanted to run a 'flush' of 5w-30 M1 through first since the previous owner used dino oil for the first 53k miles until I bought it.

    Yesterday I bought Mobil 1 "Advanced Fuel Economy" 0w-20 since for my next oil change. Ive been following the threads here on using it or not on a Gen2, thats not what Im asking though so dont flame me for another oil thread please :p

    Is there actually any appreciable mpg gains from using the 'advanced fuel economy' 0w-20 grade oil? Or is it all marketing hype?
     
  2. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    10,730
    3,221
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    2006 Prius
    Well you really made two viscosity-reduction changes, so you *might* see 2-3% MPG increase-
    (1) you vetoed the 30 weight called for in the owners manual to 20 weight (Toyota apparently OK's that)
    (2) you went with 0W Advanced Fuel economy which improves low temp viscosity.

    I plan to refill Mobil-1 AFE 0W-30 which is approved for 5w-30 vehicles. I am less brave than you, but also I gotta use up the 0W-30 on my garage shelf.

    I saw this brochure at VW service (our other car) yesterday (paraphrasing here): " to Improve MPG up to 20% - change air filter +10%, tune-up +5%, inflate tires +3%, lube oil change to AFE +2%"
     
  3. xs650

    xs650 Senior Member

    Joined:
    Jul 2, 2010
    4,539
    1,417
    9
    Location:
    Northern California
    Vehicle:
    2010 Prius
    Model:
    II
    Air filter restriction has very little to zero effect on fuel economy in gasoline cars with closed loop controlled fuel injection systems. That covers every car on the US market for the last decade.

    I don't trust any brochures in a service department, particularly a VW service department. They are there to separate you from your money.
     
    Merkey and wjtracy like this.
  4. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    10,730
    3,221
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    2006 Prius
    OK thank you for that good explanation, my VW is really a Dodge Caravan in disguise. We never talk about the air filter MPG impact here, so I was wondering.
     
  5. mmmodem

    mmmodem Taste Tester

    Joined:
    Nov 17, 2011
    2,626
    1,575
    0
    Location:
    Milpitas, CA
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    There should be some gain since you will be running a thinner oil than before. "Appreciable" is the key word here. I'm with wjtracy. Maybe 2%-3% which is imperceptible to me and within margin of error.
     
  6. xs650

    xs650 Senior Member

    Joined:
    Jul 2, 2010
    4,539
    1,417
    9
    Location:
    Northern California
    Vehicle:
    2010 Prius
    Model:
    II
    I think 2-3% might be a little on the high side. You need to know the actual viscosity of the oil, not the SAE rating. A thick 0W-20 would be a closer to a thin 0W-30 at operating temperature than it would be to a thin 0W-20.

    Viscosity at 100C

    20 = 5.6 to 9.3 cSt
    30 = 9.3 to 12.5 cSt

    If you look up their actual kinetic viscosity ranges in SAE J300, 20 weight has lot wider range in percentage than 30 weight
    9.3/5.6 = 1.66
    12.5/9.3 = 1.34

    The HTHS viscosity also has an effect and it isn't necessarily proportional to the
    so it's not even that simple.

    Short version:
    Take any individual claim a of a specific amount of savings with a big grain of salt and a guffaw. The should be a small savings and if you drive consistently and keep good records, you may be able to determine what it is for your driving conditions and the two oils you evaluate.
     
  7. ETC(SS)

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

    Joined:
    Oct 28, 2010
    5,593
    4,281
    0
    Location:
    Redneck Riviera (Gulf South)
    Vehicle:
    2010 Prius
    Model:
    II
  8. Britprius

    Britprius Senior Member

    Joined:
    Jun 14, 2010
    5,194
    1,827
    0
    Location:
    Herefordshire England
    Vehicle:
    2008 Prius
    I find an improvement in using 0w-20 oil. Huge gains? no. Worthwhile gains? yes. With UK petrol prices if I only save 1 mpg by using 0w-20 oil, over the life of the oil (10,000 miles) I save the cost of the oil. Does that qualify as an appreciable gain? in my book yes.

    The climate in the UK is somewhat cooler than the southern US states and using a "thinner oil" in a cooler climate may make a bigger difference than a hot climate.
     
    xs650 likes this.
  9. xs650

    xs650 Senior Member

    Joined:
    Jul 2, 2010
    4,539
    1,417
    9
    Location:
    Northern California
    Vehicle:
    2010 Prius
    Model:
    II
    In racing the guy that makes all the small improvements that are hard to measure or too small to measure is the one that wins, same for fuel economy.

    There is no rational reason to doubt that 0W-20 will give a bit better fuel economy then a higher viscosity oil. That's one of the reason I stick with it.

    10,000miles/50 mpg = 200.0 US gallons. 10,000 miles/51mpg = 196.1 USg A difference of 3.9 USgallons. Looks like at least the cost of a DIY oil change to me at UK petrol prices.
     
    F8L likes this.
  10. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

    Joined:
    Sep 10, 2012
    1,313
    423
    0
    Location:
    Harrison Township, Michigan
    Vehicle:
    2013 Chevy Volt
    Model:
    N/A
    I'll do anything for more mpgs..lol.

    So the consensus is that there is maybe little mpg benefit to using the Mobil 1 Advance Fuel Economy 0w-20. I like the math you did, xs650.

    I only ran the Mobil 1 5w-30 for 5000 miles thats in there right now, and its so clean on the dipstick that I feel guilty changing it... but Im excited to get the 0w-20 in there :D Whats a boy to do, lol
     
  11. 13Plug

    13Plug Active Member

    Joined:
    Apr 7, 2008
    581
    100
    0
    Vehicle:
    2013 Prius Plug-in
    Model:
    Plug-in Base
    I switched to 0W20 Toyota synthetic oil and I was happy with the result. I don't know if it was the tires that were well worn, or the thinner oil but I noticed an improvement in mpg (in my 08).
     
    kalome likes this.
  12. xs650

    xs650 Senior Member

    Joined:
    Jul 2, 2010
    4,539
    1,417
    9
    Location:
    Northern California
    Vehicle:
    2010 Prius
    Model:
    II
    Give the clean old 5W-30 to a friend with a winter beater.:)
     
  13. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    10,730
    3,221
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    2006 Prius
    Don't feel guilty changing the Mobil-1 oil at 5000. Toyota said (someone on Prius Chat asked) that it is OK to switch to the lighter 0W-20 for Gen2, but the important thing is to stick with the recommended drain interval. I go 6000 miles with Mobil-1 but believe there may be merit to holding to approx 5 to 6k. I have the extended drain interval Mobil-1 in right now, but subjectively feel engine is louder/valve noise @>5k.

    In summer you may not see big effect of lighter lube, but winter in Michigan, I gotta think you will see a MPG benefit for 0W-20.
     
  14. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

    Joined:
    Sep 10, 2012
    1,313
    423
    0
    Location:
    Harrison Township, Michigan
    Vehicle:
    2013 Chevy Volt
    Model:
    N/A
    Great idea!! I happen to have a friend who just bought an old winter beater too.
     
  15. uart

    uart Senior Member

    Joined:
    Sep 7, 2009
    4,206
    1,169
    0
    Location:
    Australia
    Vehicle:
    2005 Prius
    Hi PriusGuy32. Make sure you watch your MPG closely and document any changes. We are all interested in the results. :)

    I just changed from my (thinner) winter fill to my summer fill about a 10 days ago and have been watching really closely for any changes. Both oils are 5W30 but one is a at the lower end of the viscosity range and the other is at the upper end of the range .

    Technical data for the "oil heads".

    Winter oil: ILSAC GF-5 and Dexos1 rated. Viscosity = 58 cSt @40C, 10.7 cSt @100C. HTHS = 2.9 @150C.

    Summer oil: ACEA A3/B4 rated. Viscosity = 72 cSt @40C, 12.2 cSt @100C. HTHS = 3.6 @150C.

    As you can see there's a reasonably large change in viscosity between the two (at least as much difference as that between a light 5W30 and a typical 0W20). No change in weather conditions and only one tank on the new oil so far, but here are the preliminary results are <....drum roll.....> no change. The last few tankfuls averaged 57 MPG and the first tankful with the new oil was exactly the same.

    Maybe your results will be different due to colder climate PriusGuy. Temperatures have mostly been around 75F to 90F here recently, and will get hotter.
     
  16. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

    Joined:
    Sep 10, 2012
    1,313
    423
    0
    Location:
    Harrison Township, Michigan
    Vehicle:
    2013 Chevy Volt
    Model:
    N/A
    I think Im going to change the oil tomorrow to the 0w-20. Im going to save the very clean looking Mobil 1 5w-30 and give it to my friend who could use it as top-off in their beater car. Makes me feel better about it, especially since I got the Mobil 1 free after mail in rebate anyways.

    The 0w-20 was not free, fwiw. lol. $24 for 5.1 quarts at wal-mart.

    Anyways I want to digress intentionally for a second. Yesterday I cleaned my MAF sensor. I have 58,000 miles and just bought it 3 months ago so I wanted to check it out anyways as my mileage has been dropping like a rock lately. I have 300 miles on my tank of gas and noticed right away that my engine is no longer as choppy and rough feeling and sounding at cold starts. Score! I also noticed my average increased a whole 1mpg, and thats with 300 miles on the tank so as you know, the average mpg doesnt easily change when the miles get up there. The MAF 'bulb' was coated with soot or powder or something. I used the MAF cleaner by CRC and sprayed the bulb real good and the two little wires. I also cleaned my throttle body while I had the MAF sensor out.

    Anyways, Im hoping to get better results than Uart, seeing Im in cold weather, with the thinner grade oil :D
     
  17. uart

    uart Senior Member

    Joined:
    Sep 7, 2009
    4,206
    1,169
    0
    Location:
    Australia
    Vehicle:
    2005 Prius
    Ha, that sounds like a challenge. :p

    Better watch out though, I'm a moving target. I had an easy trip on Sunday so I hypermiled all the way to finish that first tank (on the new oil) at 60 MPG. :D
     
  18. Hi Burrito!

    Hi Burrito! Regenerative Farting

    Joined:
    Dec 9, 2012
    68
    41
    0
    Location:
    Fremont, California
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Advanced
    No flaming me, please, for a mostly oil change question. I'm a newbie.

    I have a 2006 Gen II with 93,000 miles. I've changed the oil every 5,000 miles with 5W-30 conventional oil and a Toyota OEM filter. She's running fine. I'm interested in switching over to 0W-20 for increased mileage (maybe) and increased engine life (maybe again). I would continue the change schedule of 5,000 miles, as suggested by Toyota for the Gen II.

    Question is this: What are you Gen II homeboys and homegirls using for a filter with your 0W-20 synthetic? Will the Toyota OEM be fine? My guess is yes.
     
  19. uart

    uart Senior Member

    Joined:
    Sep 7, 2009
    4,206
    1,169
    0
    Location:
    Australia
    Vehicle:
    2005 Prius
    Yes the OEM filter will be fine. Several people here are doing 10,000 mile intervals on the OEM filter without any problems.

    For your first run on the new oil just keep an eye out for any changes in oil consumption and (as always) be prepared to top off as necessary. This first run on synthetic might also clean a little more aggressively, which can load the filter a bit quicker, so sticking with 5k is probably not a bad idea. After that you could go a little longer than 5k if you want to, but obviously that's up to you. :)
     
    Hi Burrito! likes this.
  20. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

    Joined:
    Sep 10, 2012
    1,313
    423
    0
    Location:
    Harrison Township, Michigan
    Vehicle:
    2013 Chevy Volt
    Model:
    N/A
    Hi Burrito! - with a name like that who would flame you?!? :D If anything, after eating burritos, Im the one who gets 'flamed', usually the next day :eek: :LOL: hehe

    I noticed on my first run of synthetic oil (5w30 Mobil 1), my Prius consumed about 1/2 quart in the first 2000 miles. After that, no consumption at all. I put 6000 miles on that oil change with just that 1/2 quart being consumed.
    Ive driven a few hundred miles now on the Mobil 1 0w-20 and my mpg's are a little better than they were before but its only my first tank of gas since the oil change so a little early still to tell.

    One thing Ive noticed - with the 0w-20, when the engine shuts itself off at a stop, its much smoother and startups are smoother and quieter. Not as jerky. Also, with the Mobil 1 Advanced Fuel Economy 0w-20 is like $24 for 5 quarts at WalMart... how can you say no? All the cool kids are doing it... (insert cheesy teenage peer pressure PSA here) :D

    Oh and like Uart said, Toyota filters are great and preferred really. But I use Purolator oil filters, just a personal preference thats all. Last oil change (5w/30 synthetic - went 6000 miles) I used a regular Purolator classic oil filter. This oil change (0w/20 synthetic - plan on going 10000 miles) I used a premium Purolator PureOne.
     
    bobodaclown and Hi Burrito! like this.
Loading...