Mixing Different Octane Gas
07-29-2013, 06:32 PM
#1
Mixing Different Octane Gas
So, I've done some research into this already but I figure some of you might be more knowledgeable than the average poster on the internet.
It's to my knowledge that mixing octane levels yields a gasoline with an octane level of the average of the two. (ie. gas stations mix 91 octane and 87 octane in a 50/50 blend to yield 89 octane). By this logic mixing a 50/50 blend of 94 octane and 89 octane gasoline would yield a 91. Am I right in this assumption?
The reason I ask is because 94 octane is roughly .02 $ more than 91, but 89 is about .07 $ cheaper than 91. Which means if this assumption were correct, mixing 94 and 89 would yield 91 octane gasoline that's cheaper than if you were to straight up buy 91 octane gasoline by about .025 $/L. Obviously a negligible difference, but adds up in the long run. I don't believe gas stations would price gasoline the way they do if this were the case, which is why I'm asking.
It's to my knowledge that mixing octane levels yields a gasoline with an octane level of the average of the two. (ie. gas stations mix 91 octane and 87 octane in a 50/50 blend to yield 89 octane). By this logic mixing a 50/50 blend of 94 octane and 89 octane gasoline would yield a 91. Am I right in this assumption?
The reason I ask is because 94 octane is roughly .02 $ more than 91, but 89 is about .07 $ cheaper than 91. Which means if this assumption were correct, mixing 94 and 89 would yield 91 octane gasoline that's cheaper than if you were to straight up buy 91 octane gasoline by about .025 $/L. Obviously a negligible difference, but adds up in the long run. I don't believe gas stations would price gasoline the way they do if this were the case, which is why I'm asking.
07-29-2013, 07:16 PM
#3
If the pump has only one nozzle for all the different grades, how much 87 do you think you are getting before you actually get the 94 you paid for? Because of this I always fill up when my gas tank is less than 1/4 full
07-29-2013, 08:35 PM
#4
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whatever is in the tube since the flap is inside, and after that it opens the flow from the tank you've selected.
07-30-2013, 03:48 AM
#5
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Fuel station hose has a 3/4" ID. The hose is what, 8' long? That's only 0.7L
07-30-2013, 04:23 AM
#6
the math is wrong.. you're saving 0.025 per litre instead of 0.05 per litre
let 'x' be the cost of 91 gas
and suppose you fill up 'y' amount of gas
the total amount for pure 91 gas is:
x*y
the total amount of mixed 91 (94 and 89):
(x+0.02)*y/2 + (x-0.07)*y/2
=xy/2 + 0.01y + xy/2 - 0.035y
=xy - 0.025y
your total saving for 'y' amount of gas is
xy - (xy - 0.025y)
=0.025y
let 'x' be the cost of 91 gas
and suppose you fill up 'y' amount of gas
the total amount for pure 91 gas is:
x*y
the total amount of mixed 91 (94 and 89):
(x+0.02)*y/2 + (x-0.07)*y/2
=xy/2 + 0.01y + xy/2 - 0.035y
=xy - 0.025y
your total saving for 'y' amount of gas is
xy - (xy - 0.025y)
=0.025y
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07-30-2013, 04:51 AM
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the math is wrong.. you're saving 0.025 per litre instead of 0.05 per litre
let 'x' be the cost of 91 gas
and suppose you fill up 'y' amount of gas
the total amount for pure 91 gas is:
x*y
the total amount of mixed 91 (94 and 89):
(x+0.02)*y/2 + (x-0.07)*y/2
=xy/2 + 0.01y + xy/2 - 0.035y
=xy - 0.025y
your total saving for 'y' amount of gas is
xy - (xy - 0.025y)
=0.025y
let 'x' be the cost of 91 gas
and suppose you fill up 'y' amount of gas
the total amount for pure 91 gas is:
x*y
the total amount of mixed 91 (94 and 89):
(x+0.02)*y/2 + (x-0.07)*y/2
=xy/2 + 0.01y + xy/2 - 0.035y
=xy - 0.025y
your total saving for 'y' amount of gas is
xy - (xy - 0.025y)
=0.025y
07-30-2013, 05:12 AM
#9
ROTFL, what a funny thread!!! 
Here we are, spending untold dollars on bits and pieces for our S2Ks, going to the track, buying new tires every 10K kms (if you're lucky) and we worry about a couple of bucks on a fill-up?
We gotta be nuts!
I mean this in the kindest possible way, of course.
Buy the best gas you can for your car.
I'm finding Shell V Power seems to be working just fine.
Cheers,
RB
Here we are, spending untold dollars on bits and pieces for our S2Ks, going to the track, buying new tires every 10K kms (if you're lucky) and we worry about a couple of bucks on a fill-up?
We gotta be nuts!
I mean this in the kindest possible way, of course.
Buy the best gas you can for your car.
I'm finding Shell V Power seems to be working just fine.
Cheers,
RB
07-30-2013, 06:38 AM
#10
Registered User
John's thinking.. Nothing wrong with that.
At the end of the day if you save yourself... 40 bucks a year by doing this. Please account for all the extra time it takes to explain to the attendant or reswiping your card and watching the pump hit certain L to make sure you've added a 50/50 etc.
Your time is much more valuable, I'd rather use it driving
Fill up on 91 and enjoy
At the end of the day if you save yourself... 40 bucks a year by doing this. Please account for all the extra time it takes to explain to the attendant or reswiping your card and watching the pump hit certain L to make sure you've added a 50/50 etc.
Your time is much more valuable, I'd rather use it driving
Fill up on 91 and enjoy