Which Octane Fuel should you use? Putting higher octane fuel is not always better. | GTAMotorcycle.com

Which Octane Fuel should you use? Putting higher octane fuel is not always better.

taximan62

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The Gas companies try to trick you into thinking buying Premium 90 octane and Super 93 octane is better for mileage and or engine performance. All this is to just get you to buy more expensive fuel.

If your engine manufacturer says use regular 87 octane then use it. Using higher grades will not give you more power or better fuel mileage. That is all a myth.

The octane level is not a power rating of fuel like most people think. The octane level is a rating telling how resistive the fuel is to self igniting when compressed. So 87 octane is 87% resistive to self ignition when compressed and so on.

In higher compression performance engines using higher compression pistons (example 10:1 compression or higher) using regular 87 octane may have the undesired effect of self igniting before the compression stroke reaches TDC and the spark plug ignites the fuel. This is bad as it causes what is called knocking which in time will damage your engine. So these higher compression engines will call for a higher octane fuel to eliminate the pre ignition and prevent knocking.

So the bottom line is save your money and use the fuel the manufacturer recommends. Putting more expensive fuel in is just wasting your money, gives you no benefit and just lines the fuel companies pockets.
 
with a bike, have never seen any advantage in performance or mileage with premium gas,
I'm thinking half the tank gets filled with the regular gas in the hose before any of the higher octane is dispensed,
in the car I definitely see a difference in range, extra 100 km/tank on long road trips
 
Naming it "Premium" helps fool people as well. Also remember 91 RON is 87 pump octane. So read your manual carefully. It may say 91 RON.
 
in the car I definitely see a difference in range, extra 100 km/tank on long road trips

Extra range with regular or premium? What car/engine? Technically regular has more energy in it than premium. If you are getting better range from premium your ECU is playing around with fueling and/or timing. Interesting to see you get that big of a difference.
 
None of my bikes or my car call for high octane fuel so I don't use it with the exception of at the end of the season. On my last trip of the year I run the tank as close to empty as possible and fill up with premium at Shell because it contains no ethanol. I have had issues in the past with gumming up a carburetor over the winter that my mechanic felt was most likely caused by ethanol in the fuel. My snowblower and lawn mower both call for high octane fuel so I use it in them. Given that I use about 20L per season I figure I can afford to go along with what the manufacturer suggests!
 
It seems that ethanol takes it tolls on cars especially as they get older (higher kms).
I try to avoid it when possible.

Thanks Riceburner for clearing up the RON #.

I tend to find my car and bike tend to run smoother on premium and in the car I did notice getting higher km's per tank.
Nothing scientific but it looked to be about 25km more in the car.
 
Once again, depends on the car. If you have for example a 2006 CRV with the k24a1(9.6:1CR), then the difference would be purely psychological. Whereas if it's an Acura TLX with the k24w, then there would be an actual improvement, because the 11.6:1 compression calls for high octane fuel.

Any noticed difference in fuel economy would be psychological as well. As economy has more to do with driving style than the grade of fuel. And if you're watching the mileage, you'll tend to do things differently to try and get a better number.
 
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Shell's premium gas does not have ethanol. Since ethanol is like watering down your gasoline, you wonder if it's the lack of ethanol that leads to the better mileage and smoother running than just the octane 91 vs 87 - since that's just specifically resistance to combustion.
 
True, but running 91 ethanol free in an engine that requires 87 octane is beneficial

LOL - ya, but as I was getting at - I think it is beneficial only because of the lack of ethanol, and not the higher octane. I'd run ethanol-free-87 all day long if it existed.
 
On a day-to-day basis use whatever grade your owner manual tells you to use, using a higher grade gasoline is just a waste of money. At the end of the season, just before storing your bike for the winter, fill up non-ethanol gas for a tank or two (i.e. Shell Premium) to eliminate the possibility of gas/ethanol separation over the storage months + use stabilizer as well.
 
My bike says 91, and I use Shell or Costco ethanol-free. 94 would be a waste and the fuel economy would be less.

On my car, I get better fuel economy on ethanol-free 91 then I do with ethanol-dosed 94, but I get more power from the 94 by advancing the spark timing and increasing boost. Pick yer poison.
 
Ethanol provides less power for the same amount of gas....it actually is less energy dense than regular gasoline so you can see lower mileage and less power using ethanol blends. Ethanol in general is a terrible idea.
 
In higher compression performance engines using higher compression pistons (example 10:1 compression or higher) using regular 87 octane may have the undesired effect of self igniting before the compression stroke reaches TDC and the spark plug ignites the fuel. This is bad as it causes what is called knocking which in time will damage your engine. So these higher compression engines will call for a higher octane fuel to eliminate the pre ignition and prevent knocking.
So the bottom line is save your money and use the fuel the manufacturer recommends. Putting more expensive fuel in is just wasting your money, gives you no benefit and just lines the fuel companies pockets.

my bike manual says to use 86 or higher. but my compression ratio is 11.5:1 so according to the above my manual is wrong and i am damaging my engine. Usually use Shell or Petrocan. Used to always use Shell silver (89) due to only "up to" 5% ethanol. but lately been putting in regular 87
 
My bike says 91, and I use Shell or Costco ethanol-free. 94 would be a waste and the fuel economy would be less.

On my car, I get better fuel economy on ethanol-free 91 then I do with ethanol-dosed 94, but I get more power from the 94 by advancing the spark timing and increasing boost. Pick yer poison.
Last time I looked into it Petro Canada's 94 has the highest ethanol content of what is sold here. Esso's 93 is supposedly also high. Makes sense since ethanol can be used to increase octane rating.

Ultramar also has ethanol free 91 octane. On Thursdays they also charge the same for 91 as they do for 89 (at least they do this at the location near my workplace and the one they just put up near my home).

There are other places that have it as well, including in 87.

https://pure-gas.org/index.jsp?stateprov=ON

Actually from that link I see I pass a No Frills station with ethanol free 87 almost daily. Should start fueling up there. Seems to be the only station in Toronto that has it.
 
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Bit of a side note but the one thing I'm really noticing now is the greater price spread between 87 and 91. Used to be 8-10 cents a litre difference not so long ago, now I'm seeing 12-15 cents.
 
800over;2503116s Ethanol in general is a terrible idea.[/QUOTE said:
Ethanol 'enhanced' gasoline was a fable hoisted on the American public during the fuel crisis of the 1980s. All it really did was help farmers sell more corn.
 
Bike runs well on 87 with no noticeable improvements when I put 91 in the tank.
My car is custom tuned and needs to run on 91 due to spark and timing adjustments.

...octane "boosters" are also a massive waste of money.

Most people think that adding a 5 point octane booster turns your 91 pump into "96", when in actuality all you now have is 91.5
 
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Ultramar also has ethanol free 91 octane. On Thursdays they also charge the same for 91 as they do for 89 (at least they do this at the location near my workplace and the one they just put up near my home).

There are other places that have it as well, including in 87.

https://pure From time to time my ...packed with motorcycles during riding season.
 

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