I paint my plow blade and implements with rustoleum paint. I clean the metal of loose rust, then use primer for rusty metal, then paint. Mostly by brush but I have used a spray gun also.
Murph I located some Ford red and gray Valspar at a Restore place here in Ohio. At 12.50 a gallon I guess this would be a buy. We always smeared some grease on the plow's face after getting done with it.