Oil level and MPG reflections......

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Ianmeister, Feb 19, 2020.

  1. Ianmeister

    Ianmeister Member

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    So in the never ending quest to be anal about each and every .1 change in mpg I’ve made some interesting observations. I’ve been thinking hard about it. First thing I changed was an aging 12v battery. It went dead on me after parking for 4-5 days and since it was an 84 month battery that was exactly 84 months old I picked up a new one (went with Toyota everstart) After reading another account of a huge mileage jump with a new 12v I had high hopesof higher MPG and...... no difference. That was 3 tanks ago. So a few days ago I was topping off the oil. I got a little overzealous and poured in perhaps a few tablespoons more than the top mark, and something amazing happened. First thing I noticed is that the engine is FAR quieter. I can’t tell if it’s on or not and would think I’m in all electric mode we’re it not for the jolt on transition. Second is that the average MPG has crept up over the last few days .6 more than it was and still climbing. No other changes, same weather. Hmmmmmmmmm
     
  2. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    I think the opposite, lower oil level (not extremely low) would help mpg: less likelihood of crankshaft splashing in the crankcase oil, so easier spinning.
     
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  3. Ianmeister

    Ianmeister Member

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    that’s what I’ve always heard, but seriously the only thing I’ve changed is more oil. I just drove 26 minutes, the last 5 were straight up a hill and it went up another .1! This is weird.
     
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  4. Ianmeister

    Ianmeister Member

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    And another .1 today
     
  5. fuzzy1

    fuzzy1 Senior Member

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    And less oil mist to be pulled into the PCV path to eventually cause EGR clogging.

    Oh, excuse me, that is a Gen3-specific problem, not applicable to this Gen2.
    Does the Gen2 allow you to reset the MPG reading daily, so that you can directly compare daily MPGs?

    Perhaps not, that might be a Gen3-4 thing, with Gen2 only resetting automatically with tank refills.

    I have a feeling that this improving trend is just from a placebo effect on the hardware side, plus behavioral change on the operator side. Driving style alone can have a huge impact.
     
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  6. Ianmeister

    Ianmeister Member

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    #1 I can reset the av mpg anytime
    #2 eh, maybe. The thing is I wasn’t expecting anything interesting, just noticed a sudden climb in average mpg after no change for weeks. Could be coming from me. We’ll see.
     
  7. fuzzy1

    fuzzy1 Senior Member

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    While learning how MPGs change, doing this daily for a while can be very useful and informative. And if your car actually took an MPG jump for some reason, resetting the display and calculation now can give you an immediate reading on what the new improved MPG is, without waiting for the display to slowly and asymptotically catch up.
     
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  8. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    I get the impression the car has to set some base lines, and they can vary. Maybe it can get off on a different "footing" sometimes.

    I've had to disconnect the 12 volt on ours a couple of times recently, and the next few start ups has the engine doing an unusual rev up, just for a few seconds.

    Establishing a fresh baseline, and maybe that can vary some??
     
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  9. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    'Nother thought: you stumbled on some ethanol-free gas?
     
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  10. Ianmeister

    Ianmeister Member

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    Definitely no ethanol free gas here in sf Bay Area. Besides I always fill up at the same chevron station.
     
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  11. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    I filled up at a Chevron once, up the coast in a small town, and I suspect they didn't get ethanol gas: mpg was amazing good for that tank. Filled up at the same station a couple of years later, no such luck...
     
  12. Raytheeagle

    Raytheeagle Senior Member

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    I get gas at shell and I get the best mpg from it:).

    Chevron is a pricey pill to swallow:cool:.

    But when you fill up once every 3 weeks, it could be worse(y).
     
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  13. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    The different brands mostly stand united in their prices around here. Once in a while there's a half-hearted war.

    Yeah when it's half-a-tank monthly, who cares, lol.
     
  14. fuzzy1

    fuzzy1 Senior Member

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    I don't know about about your area specifically, but elsewhere, there is no guarantee that the normally labeled "up to 10% ethanol" actually contains that much ethanol, or even any at all. When supply or transport problems arise, they may temporarily sell E0 or something in between until the issues are resolved. (Substituting the other way, selling more than 10% without notice, would technically be consumer fraud.). It could conceivably happen anywhere, to any brand, even when you always use the very same station.

    And Mendel seems to have identified such a substitution that one time.
     
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  15. Ianmeister

    Ianmeister Member

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    It went up another .2 today
     
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  16. Ianmeister

    Ianmeister Member

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    And it’s now holding at 44.6
     
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