Plug gaps vary from engine size to state of tune.Union 76 is run in every car on the NASCAR Winston Cup circuit.If it didn't work,they would be using something else.Keep your gas stored in a cool,out of the sun area.Sun light destroys octane levels.Out here in MI. Union 76 sells for about $3.75 a gal.If you feel you need to run race gas,a 50/50 mix will be more than sufficiant.I myself would not store race fuel for more than 60 days.