Thought I would run some lead additive through my 1969 472 just to see the difference. Put in the bottle (empty tank) filled my tank with Super Unleaded. Right around 16 gallons. Can't tell much of a difference except when you floor it a grey "smoke screen" appears just like something out of a James Bond movie about 4 seconds into the throttle up. I'm assuming this is the lead additive as it said it contained petroleum products. The bottle said can treat up to 21 gallons so probably half a bottle would do.