Octane levels in fuels... what is best value?

[grrrr]

you can't imagine the conversations I had with the "saw coordinator" at my last job when he tried to chew me out for using regular in the chainsaws.
actually, all I remember other than a continuous loop in my head having to do with talking myself out of beating this guy, was me calling him retarded, like 3 times, and asking him how the fuck he came to "know" all this complete bullshit about octane.

Don't know why, but Stihl does recommend mid grade or better.

[This End Up]

Neezer had a excellent post, except for this one little detail:

Octane is a measure of well...octane in the fuel. it is a longer hydrocarbon chain than regular gasoline. octane has a higher flash point than the lighter hydrocarbons in gasoline.

I'm just too nerdy to let that slide.

Octane number is measure of a gasoline’s likelihood to knock (pre-combust) relative to two reference fuels. Octane number is measured by testing the gasoline in a standardized test engine. The engine is adjusted until it begins to knock. The point where the engine knocks is compared to the knock point for the two reference fuels;
- Pure n-Heptane’s knock point is defined as 0 octane.
- Pure 2,2,4 Tri-Methyl-Pentane’s knock point is defined as 100 octane.

2,2,4 Tri-Methyl-Pentane is sometimes called “octane” hence the confusion. A gasoline with a 91 octane number is 91% of the way between the knock rating of n-Heptane and 2,2,4 Tri-Methyl-Pentane. The gasoline does not contain 91% of “octane”.

[grskier]

Wow... I miss thermodynamics, but not that much.

Audi recommends "premium"
so I run premium... at 90k, I'm just writing it off as maintenance..

[RTR]

I'm in an '07 tacoma... the original (selfish) purpose for which I asked the question was to figure out if the additional 8-20 cents per gallon was worth it. I'm beginning to believe that it's not worth it... thanks for all the input.

[cramer]

its more effective on older muscle cars where compression ratio been modified etc. I know my buddies threw it in their muscle cars and it did help with power. Likely not much, but whatever. Any newer car i think the spark timing is all computerized. But im no car junky so we'd need a junky to elaborate with more scientific facts.

[mdp]

I'm in an '07 tacoma... the original (selfish) purpose for which I asked the question was to figure out if the additional 8-20 cents per gallon was worth it. I'm beginning to believe that it's not worth it... thanks for all the input.

What motor is in your Taco? If it's supercharged, it's quite possible you could benefit from higher octane. Most newer vehicles with higher compression or forced induction use a knock sensor. If it hears pinging (detonation), it either reduces boost, retards ignition timing, or both. That kills power, which usually translates to a less enjoyable driving experience, IMO.

For what it's worth, I run 92 octane in my turbocharged Mitsu. I use 92 octane and methanol injection for added octane and cooling with my other turbocharged Mitsu. I use 87 octane in my 3.4 liter Toyota truck.

[ill-advised strategy]

Don't know why, but Stihl does recommend mid grade or better.

I've seen that, it's garbage. We drove around on mandatory regular with ford V10 pinging like crazy under any load and got chewed out over running regular in 2 stroke mix.

fucking waterheads.

[carvedog]

I'm in an '07 tacoma... the original (selfish) purpose for which I asked the question was to figure out if the additional 8-20 cents per gallon was worth it. I'm beginning to believe that it's not worth it... thanks for all the input.

I don't know shit about octane, thermodynamics or any of the other technical shit at all. I do know how to divide the amount of gallons into the amount of miles. On my high mileage explorer I get 10 percent more miles ( or more ) out of a tank with Premium. I don't mess withe the midgrade stuff in my tests. I have tested this many times before I convinced myself.

Test it yourself. I am a cheap bastard and was surprised to find the premium more efficient ( cheaper ) in the long run.

YMMV LOL. Ha.