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mpiper · 03-25-2011, 05:47 PM

D Day,
That's exactly it. If the amounts of gas are equal, just divide by two. In fact, look at the octane rating sticker on your gas pumps. The way the octane is calculated is RM+TM/2 Which is Research Method + Test Method (not real name, I forget it right now) divided by 2. It's simple math. I work for an oil refining company and we only produce 2 levels of automotive fuel. If a gas station has 3 tanks, they mix the two to get the third, then pump it into the tank.

It only gets hard if you have uneven amounts of gas. but even then, the formula is simply this:

(G1*O1)+(G2*O2)/(G1+G2)

G1 = Gas1, G2 = Gas2, O1 = Octane of Gas1, O2 = Octane of Gas2.

Example: 4 gallons 89 octane and 10 gallons 93 octane
(4*89)+(10*93)/(4+10) => 356+930/14 => 1286/14 =>91.86 octane

The reason you don't divide by two is the uneven amounts of gas force you to factor in the percentage, while even amounts allow you to do the math for 1 gallon of each just to be lazy.

03-25-2011, 05:47 PM	#8
mpiper Drives: 2011 Black 1LT RS Join Date: May 2010 Location: Texas Posts: 496	D Day, That's exactly it. If the amounts of gas are equal, just divide by two. In fact, look at the octane rating sticker on your gas pumps. The way the octane is calculated is RM+TM/2 Which is Research Method + Test Method (not real name, I forget it right now) divided by 2. It's simple math. I work for an oil refining company and we only produce 2 levels of automotive fuel. If a gas station has 3 tanks, they mix the two to get the third, then pump it into the tank. It only gets hard if you have uneven amounts of gas. but even then, the formula is simply this: (G1O1)+(G2O2)/(G1+G2) G1 = Gas1, G2 = Gas2, O1 = Octane of Gas1, O2 = Octane of Gas2. Example: 4 gallons 89 octane and 10 gallons 93 octane (489)+(1093)/(4+10) => 356+930/14 => 1286/14 =>91.86 octane The reason you don't divide by two is the uneven amounts of gas force you to factor in the percentage, while even amounts allow you to do the math for 1 gallon of each just to be lazy. Last edited by mpiper; 03-25-2011 at 05:49 PM. Reason: Explaining why the 2 disappeared in the formula.