i am flushing my dad's cutlass supreme's radiator this week. do i need to remove the thermostat when flushing?

 

no, unless you want to replace it. you might as well flush the whole system. drain the coolant, add water and some flush, run it up to temp [will open t-stat] drain add coolant, voila. or you buy one of those plastic back flushers, that worked really good on my old bronco. oh yeah if your radiators pretty thrashed, sometimes you'll spring a leak. happened to me, used some of that alumaseal, haven't had a problem in 5yrs. don't burn yourself, and dispose of that stuff the right way, we've got enough crap in the rivers.