No Gain In MPG

Discussion in 'Gen 2 Prius Fuel Economy' started by Walker1, Aug 24, 2008.

  1. Walker1

    Walker1 Empire

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    Some time ago I was told on this forum by several posters that by lowering the oil level in the ICE and adding fuel injector cleaner into the gas tank that my MPG would increase. Here are the results:

    1) Lowering the oil level does nothing to increase MPG. I asked posters for proof on this matter and nobody answered me.

    2) Adding fuel injector cleaner also did not increase the MPG. I didn't mind doing it as my '06 Prius has 31,000 miles on it.

    For future reference before I will believe claims of this nature I will demand proof as to how these claims are proven.
     
  2. rfruth

    rfruth Member

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    let enough oil out & you'll burn it up then MPG will go through the roof :D
     
  3. ursle1

    ursle1 Realist

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    Are you running 10% ethanol lately
     
  4. Walker1

    Walker1 Empire

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    Both of my Prius's burn no oil & have full syn. oli in them. If the ICE has good rings & burns no oil how does it burn oil if the level is lowered?
     
  5. Walker1

    Walker1 Empire

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    Unfortunately, yes. However, I was trying to increase the MPG by trying the 2 above mentioned items. I usually get gas @ Sam's Club when I shop for bulk items weekly & their pumps mention ethanol- not to exceed 10%. Personally, I think the Gov. should dump it as our food prices are going through the roof & it doesn't save energy.
     
  6. brick

    brick Active Member

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    I think he meant burn the engine up...kill it.

    Lowering the oil is usually recommended to people who have found that it was over-filled by a dealer or quickie lube place. If it's within the acceptable range on the dipstick then you're fine. As for fuel injector cleaner, I really don't think it's necessary but once in a blue moon. Most gas these days is loaded with solvents so you may not need to use it at all.

    Is your mileage unusually low or something? Sounds like you have done just fine in your '06.
     
  7. a priori

    a priori Canonus Curiosus

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    Hi Walker. Please add a bit more information here for our benefit. Were you told simply to lower the oil level or were you told to lower it to a specific point? Is it possible that you were reading posts in which PriusChat folks were complaining about dealers or oil-change places that overfilled? This has been a common complaint in the past.

    The other information to add would be to link to the thread or threads that gave you the direction to lower your oil level. On this issue, I think it would be helpful to have you provide a direct link, as I find it difficult to believe you were told simply to lower the oil level in your engine, without any other reference point or direction.

    I see that you started a thread a bit more than a month ago, asking for more info. I also see that Bob Wilson responded, showing you a chart that exhibited his data on an MPG gain after removing oil. See Bob Wilson's response in your thread. After this posting (and a few others that gave helpful information on how to remove small portions of oil), you then asked the question about how far below the mark to go. No one responded, as far as I can tell, but it could be that people were a bit perplexed at the question. I don't recall seeing any "direction" to remove oil to any point below the dipstick level, but I could easily have missed such a post if it wasn't in a long-standing thread.

    I am certain people will take note of this, though please try to be a bit less disparaging in this regard. I see you have been a member of PC for a long time and have posted many times, and I will not attempt to lecture you on etiquette, but I will ask that you research this issue a bit more before taking such a shot at fellow members of this site.

    I have a couple of questions for you:

    1. The issue of overfilling during oil changes has been the subject of many, many threads. You can search these, fairly easily, to find out how others have dealt with the issue and whether there is any additional "proof" of lower MPGs. You've been asked this question before, but responded that you "have not used any search or advanced features since joining. I usually read posts and follow links." I know this was in response to a rather harsh post directed toward you, but I think there is some value to the question: Why not use the search feature?

    2. The other question has to do with your 2006 Prius. In your signature you note that "This car has NEVER been to the dealer for any reason." Clearly, you either DIY for oil changes or take it to a quick-change place. How much oil do you use in an oil change and how frequently do you make an oil and filter change on this car? In other words: Are you aware of any overfilling in this car?

    Hopefully, your responses to these questions will allow other PCers to give you better assistance and direction.
     
  8. john1701a

    john1701a Prius Guru

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    Sounds like a misunderstanding. The advice conveyed here has been to make sure oil isn't overfilled (higher than the full mark), because significantly above will indeed have a minor effect on efficiency. And it's a waste of oil.

    .
    How old is that suggestion? High-mileage engines could benefit in years past. But now with the inclusion of ethanol in gas, you have ever-present cleansing agent.

    .
     
  9. Walker1

    Walker1 Empire

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    At 29,500 miles I bought 4 new stock tires. The milege dropped by about 4 MPG. Now @ 31,500 miles the car is struggling to break 50 MPG with no other changes. I understand my A/C is working harder due to high heat & humidity in S. FL, but I drove the '06 here for 2 summers prior to this one so I rule that out.

    I was asking people here previously why the big drop and was told to lower the oil level & add fuel injector cleaner. There are no other variables except for ethanol since last summer.
     
  10. Walker1

    Walker1 Empire

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    Yes, I was getting 54 MPG until I had 4 new stock tires on the car @ 29,500 miles and ethanol started showing up in the gas I buy. I am @ 31,500 miles & struggling to make 50 MPG with no other changes or variables.
     
  11. Walker1

    Walker1 Empire

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    I never used the search/advanced features as I'm not familier with them. I'm not mad @ anyone. There have been times when people do not respond back after I ask them a question about their post(s).

    I do all my own maint. & oil changes. When I change the oil & filter I was going by what the owner's manual said to put in. What I did later was to take some oil out and then recheck the level. I believe it's below the full mark by about 1/8" or so. I use full syn. oil & change the filter @ 5,000 miles or so.
     
  12. Walker1

    Walker1 Empire

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    I had never heard of it before reading posts about it here. I have always done all of my own maint. on my vehicles.
     
  13. john1701a

    john1701a Prius Guru

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    Weather & Traffic have an influence. So does the engine air-filter. Sorry about no response. But you could imagine how many thousands of times (literally) some of us have seen MPG posts over the past 8 years...

    What you haven't mentioned is how often you check your tire pressure and what PSI they are kept at. That's naturally drops over time and will definitely cause lower MPG.

    .
     
  14. a priori

    a priori Canonus Curiosus

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    The Search feature on this site is fairly easy to use. You can get a quick start by using the pull-down menu on the top of each page. Still, if you'd prefer, you'll do about as well just by entering a search request in Google. The results invariably include PriusChat pages. All you need to do is type in your request as a basic question, such as: "How much oil should be used for an oil change in a Prius?" In Google, this search will give you pages from John1701a's site, GreenHybrid.com, and a Bob Wilson page, along with some PriusChat posts.

    Like John mentioned before, I'm sorry you haven't had responses to all of your questions, though I believe you've had enough info to give pretty good direction. I hope you are able to get a satisfactory answer now -- not only to the question of oil, but also on the issue of why your mileage has dropped.
     
  15. qbee42

    qbee42 My other car is a boat

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    If you only dropped from 54 to 50 mpg after new tires and ethanol, you are doing well. The tires will break in, but the effects of the ethanol won't go away as long as it is in your fuel.

    Tom
     
  16. Bob64

    Bob64 Sapphire of the Blue Sky

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    In theory, lowering the oil level to half or less CAN improve efficiency in the first 10 minutes of operation, by speeding warmup of the engine (less oil to heat = slightly faster warmup).

    I doubt you'll see any benefit in the warm/hot temps of Florida. Lowering oil levels is mainly for those people that live in cold areas...
     
  17. efusco

    efusco Moderator Emeritus
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    It took me about 4000 miles to get my mpg up to baseline after changing from my balding OEM (Japanese) Integrity tires to Michelin HydroEdge tires.

    Realize, also, that the USA Integrity tires are NOT the same as the Japanese Integrity tires...the pattern is the same but the rubber compound is different and they do have a higher rolling resistance....may be a minor factor.

    I, also, have not seen any seasoned Prius owners/MPG experts recommend the injector cleaner and wouldn't personally recommend that. And, as stated, the lower of the oil level is only in the case of overfill.

    Finally, it sounds like you may not have had an alignment done for a while, if ever. I would really suggest that you do...I won't promise an MPG improvement, but it will increase tire life and "May" give you an MPG bump. I'm on a 74mpg tank (about 400 miles in) now after having one done...normally I'd be around 70-72 with the driving conditions I've had on this tank.
     
  18. Celtic Blue

    Celtic Blue New Member

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    Bob Wilson's response seemed clear enough. His chart shows that he drained an "extra quart" of oil. An extra quart of oil is quite a lot of oil and could very well pose a problem.

    The dealers almost universally overfill with oil as they misinterpret "capacity" to mean the amount of refill oil to get them safely between the marks. The practical "between the marks" quantity is 3.5 quarts or less, not the 3.9L refill "capacity." Even in an ideal world 3.9 would put you at the full mark; in the real world any residual will put you above the mark. And it appears that Toyota calculated "capacity" a few tenths high to begin with. (This follows since my delivered vehicle was overfull and would have had the factory dry fill capacity in it--if it was a few tenths over, then the error appars to be in the refill "capacity" as well based on anecdotal reports.) You are supposed to be somewhere in between, not on the full mark.

    What does overfilling do that might harm mileage? I'm not sure. Folks have mentioned that the crank could physically be churning in the oil and that would cause considerable drag losses. Another effect could be loss of compressible gas volume in the crankcase. This would increase the effective back pressure during the stroke because it would increase pressure pulsations on the back side of the pistons on the downstroke and decrease back pressure on the upstroke (an amplitude increase.) This would increase pumping losses on both sides of the stroke. I wouldn't expect this latter effect to be very large, but I'm not sure what interaction it would have with the emission control system either.
     
  19. Walker1

    Walker1 Empire

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    I usually check tire pressure every 2 weeks and put 42 lbs. in the fronts & 40 lbs. in the rears.
     
  20. Walker1

    Walker1 Empire

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    I didn't know that the new Goodyears had different compounding. I had asked several times to posters on a tire replacement post to tell me the make & model of a tire that would equal or exceed what I was averaging on the stock tires. Nobody ever told me they saw an increase in their MPG so I ordered the stock tires figuring I'd get the same MPG.

    As to fuel injector cleaner- I put 1 bottle of Lucas's in a tank and that's all.

    Here in FL 30,000 miles is about all you can expect out of many tires due to extreme heat and what is used to build the roads. When I retired those tires the tread was uniform and even on all 4.

    As to ethanol- I wish our Gov. would stop using it as it's pretty worthless and food prices are going through the roof. In addition, it's using just as much energy to produce it.

    I have been told and read many posts here about poor milege due to ethanol. Bad idea. Thanks for the info on the tire compound.

    Perhaps when the hot summer ends the A/C unit will not be working as hard & my MPG will pick up.

    On another note: My 2008 Prius is just barely averaging 47-48 MPG with about 3,400 miles on it. I guess time will tell.;)
     
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