[Bill Pritchard]

Some antifreeze gets into the oil and in a few days of easy use the motor is ruined??? I'm not sure that seems reasonable. I had that happen one time on my wife's 84 Monte Carlo SS....it sucked an intake gasket and we got antifreeze into the oil. Oil looked like a chocolate milk shake and was way over-full. I tore the heads off to have magnafluxed (they were notorious for thin casting walls), flushed the engine out, put everything back together and drove it for many more years with no issues.

If your dad is thinking of trading anyway, then he's probably best to trade it in as-is and let the dealership deal with any more problems that might crop up, since they will undoubtedly just put a new short block in it and reuse heads, thermostat, oil pressure sender, etc.