Following a long and late conversation, we would like to point out again: The miracle cures that are recommended to make your classic run more efficiently, nicer, better and faster, that….
do not work.
Just as humans used to think of ground owls' eyes to be able to derive unprecedented powers, so modern consumers expect (or rather hope) for the wonders of additives, things and 'just screw them in' that us through The Net, Tell Sell and scholarships are presented.
In America, a lot of those miracle remedies have recently been tested again. Of the 104 devices and additions, 97 were found to have no or even negative effects on the engine and fuel consumption.
The resulting 'plus values' were all in the tolerance range of the measurements.
So just give your classic carer good maintenance and use resources from a trusted source. As well. Much less expensive.
Oh yeah; the most recent hypes are the addition of acetone to the gasoline (can affect light metals and gaskets) and a bubbler that turns water into water (dust) gas, which means that the power also has to increase enormously. Almost as much as it takes in capacity to dissect that water.
Remember: Only Gandalf can do magic