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Premium Gas

Discussion in 'Gen 3 Prius Fuel Economy' started by eightiesdude, Aug 21, 2014.

  1. eightiesdude

    eightiesdude Junior Member

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    I have been lately spending a bit more on premium shell gas. I think I notice a slight increase in acceration but maybe its just me. What is your experiences with our cars using premium gas?
     
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    E0 gas gets 4% better gas mileage than E10.

    Some Prius c owners claim their engine computer can adjust for premium, Toyota has not documented that.

    No other Prius owner sees improved MPG from premium with the same percentage of ethanol as regular. Bob Wilson hints that premium may provide more power during hill climbs.
     
  3. eightiesdude

    eightiesdude Junior Member

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    Ah so it seems not me about premium. Finding an E0 station maybe something I may look into too.
     
  4. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    In my area, E0 is more than 4% more expensive, so I stick to E10. This varies by area,
     
  5. lester williams

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    E0 is $3.52 here,, Shell E10 regular is $3.05,, guess which I use..... [ I did, however, try 2-3 tanks of the E0---- I cannot distinguish any improvement in mpg ]
     
  6. ETC(SS)

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

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    I've tried E0.
    I didn't notice any difference, and if I'm going to pay 40-50 cents a gallon more for fuel, there needs to be a 40-50 cent per gallon difference.

    'Premium' fuel isn't "premium"...it just has a higher octane level.
     
  7. Goin2drt

    Goin2drt Junior Member

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    My dealer told me that you will actually get a little worse mileage with premium as the computers can't adjust for it or something. I just figured he was full of crap and use regular anyway.
     
  8. wjtracy

    wjtracy Senior Member

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    Regular is recommended as it is cheapest and Shell is TopTier.com rated, so the additives are fine in Regular.
    Premium and E0 can sometimes contain a little more energy content (better MPG) but its usually a minor difference and not worth the extra cost.

    I got some Premium the other day just for the heck of it. I was out of my local region so it was my first chance for me check energy content outside my region. Well it was the highest energy content I've seen but not as high as I was hoping...not much different than my usual regular (I've been getting accurate weight on 1.5-gals to estimate density/energy content). I might have a chance at a E0 sample this week on a road trip...none anywhere around me. See Pure-Gas.org for E0 stations in your area. FL is getting more E0 as FL recently removed the statewide E10 mandate.
     
  9. Okinawa

    Okinawa Senior Member

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    You are wasting your money buying premium. Your car is designed to operate on regular.
     
  10. fuzzy1

    fuzzy1 Senior Member

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    Sometimes, premium can also have less energy content that the regular octane, depending on circumstances that the customers are unlikely to know. And these circumstances will vary by location, season, and supplier.

    So the dealer above is not necessarily full of crap on this particular issue. But that is a good general assumption to make, until demonstrated otherwise.
     
  11. DAWg134

    DAWg134 Junior Member

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    I think that whether or not you see a difference in gas mileage between regular and premium depends upon your particular driving habits. All modern internal combustion automobiles, including the Prius, have a knock sensor installed. The purpose of the knock sensor is to retard the ignition timing whenever it senses pre-ignition (i.e., detonation, or "engine knock"). The ability of the engine to adjust its timing is what allows it to use a lower-octane fuel. Thus, modern cars do not "need" higher-octane gas in order to operate.

    However, retarding the ignition does at a price... a reduction in both power and efficiency. Those of you who may have had an opportunity to work on a car prior to the widespread implementation of electronic ignition will recall that the nominal ignition timing had to be manually set under a specific set of operating conditions of engine speed and (sometimes) vacuum. Typically, the timing was set at idle such that the spark plugs would fire somewhere between 10-20 degrees before the piston reached the top of its stroke (e.g., maximum compression). When driving, a set of centrifugal weights would further advance the timing as engine speed increased, whereas engine manifold vacuum would further advance timing based upon the load imposed upon the engine. It was not uncommon to see the timing advance to 40 or 60 degrees Before Top Dead Center (BTDC) just by rev'ing the engine under no-load conditions.

    If you stomped on the gas and/or rev'd up the engine while driving, you would often hear the engine knocking. If this happened, it was time to either change your driving habits or head back to the garage and a) reduce the timing, b) fool around with the points... or c) simply fill up the tank with premium gas or even racing fuel. If you weren't racing your buddies and didn't mind the loss of power, the easiest thing to do would be to retard the timing. This is essentially what the modern electronic ignition system does. You do lose power. You also reduce the fuel efficiency since you're effectively reducing the compression to a non-optimal ratio. However, unless you regularly operate your vehicle under heavy loads (e.g., driving in mountains, towing a trailer, or "lead-foot" starts at the traffic lights), it's unlikely the knock sensor would come into play very often. Since most Prius drivers operate their vehicles with a feather touch on the accelerator, it's unlikely that very many would benefit from premium fuel.

    I've only owned my Prius for a couple of months and have only used regular fuel, so I have no personal experience with the use of premium in a Prius. However, I do have 10 years of gas mileage data with my former Toyota Tundra pickup. My experience with that particular vehicle was that I realized an 8% increase in gas mileage whenever I filled with premium. So.... whenever the price speed was less than 8%, I filled with premium - otherwise, it was regular gas that went into the tank. With gas hovering around $4 per gallon in southern California and the price spread between regular and premium only 20 cents, it was generally premium in recent years since the break even point was $0.32.
     
  12. Easy Rider 2

    Easy Rider 2 Senior Member

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    AAAARRRRRGGGGGHHHHH !!!!
    Not AGAIN.

    Doesn't ANYBODY ever look for previous discussions before posting the same old question for the ten thousandth time ?????

    Sorry, had to get that off my chest.

    But really, it has been discussed to death already.
    Please look.
     
  13. eightiesdude

    eightiesdude Junior Member

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    I may try to find an E0 gas in my area to see the difference.
     
  14. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    About 50 cents a gallon.
     
  15. -1-

    -1- Don

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    ;)TWO things I've learned about my Prius here, Toyota recommends:

    1. Regular gas.

    2. 10,000 miles or one year between oil changes.

    I don't have to be told twice.
     
    #15 -1-, Aug 22, 2014
    Last edited: Aug 22, 2014
  16. Feri

    Feri Active Member

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    Australian Prius had a sign on the inside of the fuel flap saying E10 can be used but Premium fuel is recommended. I can upload a photo if necessary. I believe the octane of US premium and Aus premium is essentially the same.
     
  17. Feri

    Feri Active Member

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    The benefit becomes apparent with long term use. My experience of using Premium in cars other than Prius is that there is a slight improvement in FE but not really noticeable at the pedal. The real gain is the cleanness of the combustion chamber and longevity of the motor. I have never used anything but in my Prius. I have previously uploaded pictures of the cleanliness of the inlet chambers in the head.
     
    orenji likes this.
  18. Feri

    Feri Active Member

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    With advanced engine cleaners!
     
  19. Okinawa

    Okinawa Senior Member

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    Before I retired I had a job that I made inspections at all the major refineries in my area and there are some very big ones. I asked the number 1 authority for a major oil company in the U.S. about this very issue. He said if your car is designed to operate on regular grade gasoline you are wasting your money by going to a higher grade. He said if you are going to drive in mountainous (flat in my location) country it would be a good idea to move up to mid grade gasoline as a precaution because you do not know what the anti-knocking device in your car is doing and if any wear is being inflicted on it. I will not disclose the name of the oil company or the location of the person that told me this. This should put this matter to rest forever but you can sure bet it will not. Bye.
     
  20. bwilson4web

    bwilson4web BMW i3 and Model 3

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    When I was testing gasolines in our 2003 Prius, I did not test mid grade, just premium. I was not really interested in checking octane grades between the lowest and highest. There was evidence at maximum power settings on a hill climb there was some slight tuning to use the higher octane fuel BUT it was midway between the high energy and lower energy content gasolines.

    Testing mid grades is not on my 'bucket list.'

    Bob Wilson