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Thread: Does using Premium gas have any negative effects? (2015 CVT ES)

  1. #31
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    Quote Originally Posted by Cleartec View Post
    I would be more than happy if anyone with the posibility to dyno test the mirage with and without premium gas to see if there is a difference...
    You would have to dyno the car with one type of fuel, leave and switch over to another type of fuel and drive the car for at least about 3 tanks of fuel before dynoing again.


    Certified holder of useless car knowledge.

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  3. #32
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    If by premium gas you mean higher octane, than I do not believe that you will see positive or negative impacts with respect to vehicle performance and longevity. Running 93 octane vs 87 octane is only going to cost you more without benefit. I am an advocate for top tier gas because it does have good additives and detergents, not to say bargain stations don't also, just there is no accountability with them. The best things that you can do is to keep the tank full (87 octane helps with this $) as it reduces condensation in winter and is better for the fuel pump. Also don't let the gas get very old (try to burn through it in no longer than one month).

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 automatic: 46.2 mpg (US) ... 19.6 km/L ... 5.1 L/100 km ... 55.5 mpg (Imp)


  4. #33
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    Yesterday I bought 22.5 gallons of Shell regular for $1.349@ gal, CASH ONLY, just because it was the cheapest within 20 miles. January 9th to yesterday was 1190 miles. 2.6 cents a mile, $30.35 for one months fuel. Coldest part of the year here just under 53 mpg

    16.5 gallons in jugs waiting to refill the car.

    I buy the cheapest I can find. Keep my wallet heavy .

    regards
    mech
    Last edited by deleted user; 02-10-2016 at 06:37 PM.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage de 1.2 manual: 55.7 mpg (US) ... 23.7 km/L ... 4.2 L/100 km ... 66.9 mpg (Imp)


  5. #34
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    Quote Originally Posted by namco View Post
    There was a study done in Canada by a Canadian news station where they talk about fuel octane. They took a chevy pos and put it on the dyno with regular, drained the tank, and ran it with premium, and nothing happened between power wise. They then checked how it tested emissions wise and noted that when they put premium in, the car was expelling un-burnt fuel IE the car wasn't taking advantage of said higher octane. I wont go into how dumb the people in said news were including the retard expert they had on.....

    It was a ****ty chevy which I think all american cars are junkers. The biggest problem with american cars are the lack of engineering. The only american cars that can adjust to different fuels from factory are those with flex fuel sensors, aka the ecu is able to tell the difference between 89, 91, 93, and e85, and any ratio mix of both. Even my STI can self adjust to lower octane fuel, granted you lose power and its noticeable. (many subaru sti owners are retards and don't realize the knock sensor helps the ecu retard timing when you use lower octane fuel, you almost never hear of lower octane blowing a motor because most import cars self adjust anyway).

    personally I will be using 93 octane after my first tank of gas is used up, I'm 90% sure the dealer put in regular to top it off, which is no big deal to me. once the tank is nearly empty it will be 93 time.
    That test was worthless from the start. The ECU takes up to three tanks to re-learn, (yes literally learn), how far it can push timing without knock and thus make more power. It is well known that some cars, usually mid to higher power cars, will make slightly more power on higher octane. In some Lexus owners manuals it states this specifically. That's why racing fuel is 100 octane not 80.

    To the OP, nothing detrimental will occur using higher octane.

    In Southern Cali its 85 degrees right now, our **** winter blend 87 octane (which has 10 percent ethanol), which is designed for colder weather, is producing what sounds like knock so I am using 89 octane which seems to help. But to be fair I don't know if what I am hearing is true knock or something resembling knock but there is a definite ping on very very light throttle at low speed.

  6. #35
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    Quote Originally Posted by ahausheer View Post
    That test was worthless from the start. The ECU takes up to three tanks to re-learn, (yes literally learn), how far it can push timing without knock and thus make more power. It is well known that some cars, usually mid to higher power cars, will make slightly more power on higher octane. In some Lexus owners manuals it states this specifically. That's why racing fuel is 100 octane not 80.

    To the OP, nothing detrimental will occur using higher octane.

    In Southern Cali its 85 degrees right now, our **** winter blend 87 octane (which has 10 percent ethanol), which is designed for colder weather, is producing what sounds like knock so I am using 89 octane which seems to help. But to be fair I don't know if what I am hearing is true knock or something resembling knock but there is a definite ping on very very light throttle at low speed.
    Torque Pro will report timing advance and you can plot it. Also estimates WP from accelerations just need perfectly flat road and no wind.

    From the tests we done there was ~5% MPG improvement with higher octane, but the price difference was greater. So not worth. Engine did run smoother and there was perception of more output at lower RPMs/light throttle, but I haven't looked at timing back then.

    CA gas is crap, last time I took my bike there (has open loop EFI) it was refusing to run on it at 6-7,000' altitude.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


  7. #36
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    I use 98 octanes instead of 95. My old car was from Smart and had a 1.1 75hp mitsubishi engine, i started using the recomended 95 gas but i was always geting the engine light and safe mode...going to the dealer and paying for cleaning and checking..
    Then i contacted Smart importer about the gas and they told me the better the gas the better the performance of the engine. Never had the light and i kept the car 12 year, had the butterfly checked several times always clean.
    So in my Space Star i only use the best gas at 1.77/1.85 euros. Gas here its very expensive so is having and keeping a car.

    I wish here we still had Shell 100 octane.. I used it a lot in the Smart, greater milleage.

  8. #37
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    I had a Cadillac Deville that required 91+ octane for achieving a compression ratio of an oddball engine. (non northstar in a 1995 made by GM)

    Once my gf filled it with 87 octane, it ran like crap. It was very noticeable though.

    Also I've never done the math, but my miata does perform just a tad better with noticeably better gas mileage.

    I'll probably use premium all the time since it's only +.20-40$ more expensive.

  9. #38
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    Quote Originally Posted by Kungpaoshizi View Post
    I had a Cadillac Deville that required 91+ octane for achieving a compression ratio of an oddball engine. (non northstar in a 1995 made by GM)

    Once my gf filled it with 87 octane, it ran like crap. It was very noticeable though.

    Also I've never done the math, but my miata does perform just a tad better with noticeably better gas mileage.

    I'll probably use premium all the time since it's only +.20-40$ more expensive.
    Owner manual states - "Your vehicle is designed to operate on unleaded gasoline having a minimum octane number of 87 [(MON+RON)/2] or 91 RON."

  10. #39
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    Quote Originally Posted by Mark View Post
    Owner manual states - "Your vehicle is designed to operate on unleaded gasoline having a minimum octane number of 87 [(MON+RON)/2] or 91 RON."
    Oh ya, I saw that.

  11. #40
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    Quote Originally Posted by Mark View Post
    Owner manual states - "Your vehicle is designed to operate on unleaded gasoline having a minimum octane number of 87 [(MON+RON)/2] or 91 RON."
    You won't see much of a difference in economy between 87 and 92 octane. But you probably WILL see a difference between 92 octane E0 and 92 octane E10. I did.



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