As others point out, the glow plug will loose most of its ability (if it works at all) to ignite the mixture if enough methanol is not in the mix.
This is a myth that is wrong and actually 180 degrees backwards. Glow plugs have been used on gas engines with success. First as research engines, and more lately with large gas engines. The problem with gas is our plugs are made for methanol which has an auto ignition temp around 500 degrees C. Gas has an auto ignition around 280 degrees C or so. So our plugs are too hot. Still with a very cold plug and some methanol added to the mix some modelers have had success with the very mix he posted. See the engine conversion forum for the results.