Re: Body Bolt Resto A simple How To
 

Manganese(or Zinc)Phosphate coating is small iron phosphate crystals on the surface, and will be dark or light grey color. An oil dip is done after the phosphate crystals grow by chemical reaction. The purpose of the oil is to saturate the coating and provide vastly increased corrosion protection. Phosphate alone is almost no corrosion resistance, but is crucial to help the oil stay on the fastener. This is a barrier coating to prevent moisture form getting to the steel. The phosphate plus oil is better than either phosphate or oil alone, they help make each other work better. Phosphate is cheap.

Re: Body Bolt Resto A simple How To
 

I know you can get a phosphating kit from year one. Not sure if it's the same thing you guys are already doing?