If you want to lubricate the valve guides (and raise the octane rating slightly) add a gallon of Diesel fuel to 19 gallons of gasoline. It's just as effective as lead additives and/or "octane boosters" It slightly increases the specific gravity of the gasoline, and slows down the burn rate, both of which have the effect of a slightly higher octane fuel. A gallon of Diesel costs less than a pint of "additive" also.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!