Todays cooling systems run at higher pressures and temperatures but "back in the day " my grandfather used to use "oatmeal", he'd just throw a 1/2 cup dry regular Quaker Oats or so into the radiator and run it, I withnessed it work twice. stopped the leaks after an hour or so of running and the plug lasted over a year one time and the second one lasted longer than he did! at least four or five years, on 1960s-70s pickups. These where pickups that ran five days a week in his nursery business. He was born in Colonge, Germany 1896-1982,Smart?Cheap? either way it worked! Good Luck