So, discovered a core plug leak the other day. Drained the block, popped it out and now am awaiting the replacement to arrive (apparently, all of the stores in this area have only the 'deep' ones and mine was definitely shallow). Anywho, I have heard that some folks back in the day would coat the inside or backside of the plug (the part that will have coolant flowing past it) with something to cut down on corrosion over time. Essentially, if there is a barrier between coolant and metal the breakdown is less??