1. Toluene: Common ingredient in Octane Boosters in a can. 12-16 ounces will only raise octane 2-3 *points*, i.e. from 92 to 92.3. Often costs $3-5 for 12-16 ounces, when it can be purchased for less than $3/gal at chemical supply houses or paint stores.
    

2. Xylene: Similar to Toluene. 12-16 ounces will only raise octane 2-3 *points*, i.e. from 92 to 92.3. Usually mixed with Toluene and advertised as *race formula*.
    

3. Methyl-tertiary-butyl-ether (MTBE): Oxygenate. Very common in octane booster products. Has lower BTU content than toluene or xylene, but oxygenate effect makes the gasoline burn better and produce more energy.
    

4. Methanol or Ethanol: Methanol is wood alcohol. Ethanol is grain alcohol and found in Gasohol in 10% ratios. Both alcohols are mildly corrosive and will eat gas tank linings, rubber and aluminum if used in excessive ratios. Main ingredient in "Gas Dryers", combine with water.
    

5. Isopropyl Alcohol and Tertiary Butyl Alcohol: Similar to Methanol/Ethanol. Isopropyl Alcohol is simply rubbing alcohol.
    

6. Note 92 octane in table above, California only has 91 octane as of Aug 2002.
   Which brings up still another subject, Why are we only getting 91 octane at 92 prices?
   It seems the oil pipeline people wanted to standardize premium gasoline in their pipelines
   so that they could save time and money by making fewer switches, fewer holding tanks required
   and less product ( interface ) going to slop tanks. An all around savings for them.
   Now here's were the consumer gets screwed. Pipeline asks the refiners to produce just
   91 octane for their premium gasoline, they say " OK ". After all, 91 costs less to produce than
   92 octane and we'll sell it for the same price. Refiners win win. Pipeline win win. Consumer screwed.
   Own a high performance car, truck, dune buggy, boat or motorcycle? you're screwed.
   Now more than ever, these consumers must make up their own gasoline blends or detune.
   Ok, that's my two cents.

Making your own

100 oz of toluene for octane boost
25 oz of mineral spirits (cleaning agent)
3 oz of transmission fluid (lubricating agent)

This product is advertised as "octane booster with cleaning agent *and* lubricating agent!". Diesel fuel or kerosene can be substituted for mineral spirits and light turbine oil can be substituted for transmission fluid. Color can be added with petroleum dyes.

Or skip the cleaning agent & the lubricating agent altogether. Most high dollar gasoline comes
with cleaning agents already, and does any brand of gasoline come with a lubricating agent? No.
It's not needed.