[A930Rocket]

I drained and filled it about one and a half ago, when I replaced all of the coolant hoses, thermostat, water pump, etc. And then replaced coolant again in six months ago when I need some bottom in engine work.

In the old days, they have a kit that you tied into the heater hose and flushed the engine that way. Looking online, there are several brands of coolant flush. Obviously, I would want one awards with plastic and aluminum.