Most of the old aerosol penetrants used isobutane/propane as a propellant. The EPA put the kibosh on that some time ago. Now they use CO2 or other inert gas and thus it will not start an engine. The way to tell that change is to look at the output stream, if it is fan shaped it is isobutane/propane, if it is a solid stream it is some other gas.


W. E. Boyd