I once heard this from a senior relative and there was no way for me to verify it. Years ago one of the neighbours of the said relative bought a used car, and before long he noticed that there was always some clunking noise from the rear end. He checked the suspension and bearings to no avail. Finally a Joe Sharpeye mechanic nailed down the gas tank, and took out 2 marbles after a shop surgery. The mechanic said that some time ago marbles like those were sold and claimed to be a sort of gas cleanser... which sounds like a load of crap. However, nowadays many namebrands are still doing the same, no longer on gas tank, of course. Anybody gives us an example, please? [metal]
