Octane ratings...

**PatrizioD** · 10-24-2008, 05:14 PM

Ok I'll bet most of you agree this is a stupid question, but I'm posting it anyways, because me and my father are both wondering.

I have an 06 GTO tuned for 91 octane gas. If I can find 91 around here in New England, its the same as 93 at all the other stations, so I use 93 instead. I know this sounds like a cheap ass idea, but if I put 5 gallons of 89 in, and 5 gallons of 93 in, would that give me 10 gallons of 91? Or are the mixtures and formulas incompatible? Thanks in advance! Oh and I havent tried this, probably wont. Not that desperate to save money...

**Sarge** · 10-24-2008, 05:58 PM

Fair question and understandable in this day of bullshit gas prices. But here is the deal on Gasoline "mixology"......
The add packs do not mix. Lets say you get 50% 89 Octane and 50% 93 Octane. Math would tell us one could expect 91 Octane. But unfortunately you get a tankful of half and half....the two do not mix. You could be running WOT to impress the girls and get a big ol gulp of 89 Octane and get detonation. So sweet and short is the add packs do not mix to form one Octane but remain two octanes in one tank.

**jknelms** · 10-24-2008, 06:23 PM

Originally Posted by Sarge

Fair question and understandable in this day of bullshit gas prices. But here is the deal on Gasoline "mixology"......
The add packs do not mix. Lets say you get 50% 89 Octane and 50% 93 Octane. Math would tell us one could expect 91 Octane. But unfortunately you get a tankful of half and half....the two do not mix. You could be running WOT to impress the girls and get a big ol gulp of 89 Octane and get detonation. So sweet and short is the add packs do not mix to form one Octane but remain two octanes in one tank.

that's a good amount of knowledge to remember.

now for a good diagram on the molecular level of why the two do not blend.

**PatrizioD** · 10-24-2008, 06:31 PM

Good to know, thanks Sarge.

**Sarge** · 10-24-2008, 06:46 PM

Originally Posted by jknelms

that's a good amount of knowledge to remember.

now for a good diagram on the molecular level of why the two do not blend.

Well I maybe misleading a tad....let me elaborate.....at most gas stations they do mix 87 octane and 93 octane to make the 89 octane....it is coming from only two tanks and they do mix it......but

the blends are made specifically to blend....if they are not formulated to blend they wont.

**jknelms** · 10-24-2008, 06:50 PM

Originally Posted by Sarge

Well I maybe misleading a tad....let me elaborate.....at most gas stations they do mix 87 octane and 93 octane to make the 89 octane....it is coming from only two tanks and they do mix it......but

the blends are made specifically to blend....if they are not formulated to blend they wont.

i can understand that. I'm somewhat educated....i had a college inorganic chemistry class and made a B in it....

**Sarge** · 10-24-2008, 07:18 PM

Well.... there are like 23 base stocks for this countries gasoline supplies. Many suppliers have proprietary blended base stocks. Like Texaco/Chevron have theirs and Shell has theirs etc. etc. Most gasolines are bought at third party resellers.....not suppliers...so they buy on the spot market and may buy 93 octane from supplier A and 87 Octane from supplier B. The two are not compatible and will not mix. Now if your at a Mobil station yes you can mix. 70% 93 and 30% 87 will get you 89 Octane. Ain't worth it in my humble opinion.

**jknelms** · 10-24-2008, 07:24 PM

Originally Posted by Sarge

Well.... there are like 23 base stocks for this countries gasoline supplies. Many suppliers have proprietary blended base stocks. Like Texaco/Chevron have theirs and Shell has theirs etc. etc. Most gasolines are bought at third party resellers.....not suppliers...so they buy on the spot market and may buy 93 octane from supplier A and 87 Octane from supplier B. The two are not compatible and will not mix. Now if your at a Mobil station yes you can mix. 70% 93 and 30% 87 will get you 89 Octane. Ain't worth it in my humble opinion.

which the key point to this is, Each supplier has a unique concoction of fuel that is not able to mix well, or at all, with other supplier's blends, due to additives. Which, brings the next question, which is slightly off topic, but what Supplier/Retailer fuel do you recommend? I do remember your article about mixing a small percentage of oil to 5 gallons of gas for lubrication of combustion internals. but who has the best fuel over all? I'm biased to ExxonMobile for psychosomatic reasons.

**Sarge** · 10-24-2008, 07:35 PM

Top Tier Gas suppliers must adhere to a strict set of guidelines....
I stick with Shell/Texaco/Chevron
http://www.toptiergas.com/retailers.html

**jknelms** · 10-24-2008, 07:42 PM

Originally Posted by Sarge

Top Tier Gas suppliers must adhere to a strict set of guidelines....
I stick with Shell/Texaco/Chevron
http://www.toptiergas.com/retailers.html

I've heard (hear-say, rumored from Gear Heads in Dallas.) that Chevron with Techron wasn't good for an engine. I'm guessing that's a load of BS then, seeing as with that technology, they were the first to be on the TOP TIER.

**adam3566** · 10-24-2008, 09:24 PM

Been a fan on mobile for YEARS! Never had a problem with them at all. If i have to fill up with something else, try to get BP.

**adam3566** · 10-24-2008, 09:25 PM

Originally Posted by jknelms

I've heard (hear-say, rumored from Gear Heads in Dallas.) that Chevron with Techron wasn't good for an engine. I'm guessing that's a load of BS then, seeing as with that technology, they were the first to be on the TOP TIER.

Alot of stations these days are BSing people with this great technology that helps improve engine life and gas mileage. To me it's mostly bullshit.

**Sarge** · 10-25-2008, 05:05 AM

Gas is dry and corrosive as hell. Thus the 2stroke management project and the results speak for themselves. What I am after in a top tier gas is no water/sand.