Wouldn't you want hotter plugs to try and burn the crud off? At any rate, I think you should park the car until you get it fixed. Too much pre-ignition and you might hole a piston plus if the coolant gets into your oil, kiss your bearings goodbye. Sorry I can't tell you the numbers you seek but perhaps the Motorcraft website or some other website would be of help.

Karl


*** It's all about consistency! ***

98 SVT Contour
86 Ranger GT
69 Fiat 850 Sport Spider
67 Formula-S Barracuda