Octane Mixing

[cerbomark]

There was a post about octane mixing(which I couldnt find) but some very convincing arguments were made stating you don t get the average of the two octane blends that are mixed. Ex: 87 mixed with 93 =90 octane. OK, Now I read a newpaper article about a local gas station that is having new tanks put in. One is for reg, the other is for preimum and the another will blend the two for the mid grade. I don t know but something doesn t sound right.Anyone ever hear of this?

[Tyler_LS1]

This is the first ive heard of it.

[Nytemare]

who cares about mid grade anyway.

 

either run regular or premium.

 

why even bother making something like a mid grade...I'm sure it costs more to make 3 grades than just 2...so drop one and pass on the savings.

[pwall]

I could be wrong (wouldn't be the first time... ), but up North, gas stations have 87 and 91. These two are mixed to give 89.

(some gas stations...ie. Sunoco, have 94 as well).

 

I remember one time when a local gas station ran out of 87 and ended up selling the 91 at 87 prices. Some poeple wondered why they couldn't get 89......

[silverad03]

who cares about mid grade anyway.

 

either run regular or premium.

 

why even bother making something like a mid grade...I'm sure it costs more to make 3 grades than just 2...so drop one and pass on the savings.

Probably the same people that buy 3/4-ton trucks, medium fries, and 32 oz. fountain drinks - those crazy b*st*rds!! Some people need/like to run a higher octane but don't have the pockets to run premium - it's a compromise thing, most bang for your wallet, keeps that market segment happy and nets the oil companies more profit.

[cerbomark]

The northeast has 87, 89,91,93 depending on the company.

[Nytemare]

LOL....don't have the coin to run premium...

 

I have a 98L tank...a tank of regular costs me 103$ from dead empty. and a tank of supreme is $115. I usually only pay about $70 as my tank never goes below 1/4

 

I get better economy with the supreme than the regular, so it ends up that my yearly fuel bill actually costs me less by running supreme.

 

Just my $0.02

[cerbomark]

My original post was only in ref. to someone posting if ocatne blends are mixed what octane you end up with. My truck runs fine on mid grade with the pcm tune I had done. I was wondering about the gas stations under ground tank mixing thing I read about. I know the topic of what octane to run has been beaten to death and everyone had a differnt view of if too high of an octane for a motor not made for it was bad.

[Nytemare]

Ok...its not a straight forward calculation.

 

(93+87)/2 does not equal 89 for octane.

 

its actually calculated like this:

 

O#1 - Octane of Fuel number 1

O#2 - Octane of Fuel number 2

O#R - Octane of Fuel number Result

GF1 - Gallons of Fuel 1

GF2 - Gallons of Fuel 2

GFT - Gallons of Fuel Total

 

Formula; O#1*(GF1/GFT)+O#2(GF2/GFT)=O#R

 

In order to get an 89 octane fuel, you'll need a 2:1 mixture of 87:93 octane. However its a 1:1 ratio of 91:87

 

Heres an excel sheet I found that calculates this stuff.

 

http://www.gnttype.org/techarea/misc/octaneblend.xls