Mark,
Have you ever looked at the JC whitney catalog?

Curb feelers sold by them give you better fuel economy.
So do the Hula Girls.
So do the spinner hubcaps.
So do the chrome tail pipe extensions.
So do the Blue Dot's.
So do the chrome spikes that bolt on the vent shades.

With this in mind, if that sales person told you you would get better
gas mileage with this "Miracle in a can"---go for it!!

I have truly heard it all now.:>)

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Terry
74 Westy (Clementine)
85 GL