I usually pour a couple of capfuls of Marvel Mystery Oil into the tank before I fill it up.It gives the top end a little lubrication,keeps the carb clean,and,for some reason,seems to up the octane a little,too.
Speed


1954 GMC 350
1957 GMC 1/2 ton
1962 Chevy C-30
1952 Chevy 6400 dump bed project truck
'98 Harley FLSTC
'66 Pontiac Catalina
'76 Chevy 1 ton Duallie
'84 Bronco II
'78 Dodge W-200
'81 Toyota 4X4 truck