For what it's worth . . . I've used several smoke machines. If you want the best . . . go with the Vac-u-tek that uses Dry Nitrogen as a propellant source and a ultra-violet smoke that is easily detected with a Black Light. It's a DO-ALL machine that's well worth the additional money spent (approx $2K). I've used them for leak testing intake, evap and PSE systems. I know you can get OTC machines for much less, so I guess that depends on your budget.