[drover]

First off don't use tap water, even no matter how good its supposed to be it always has some minerals in it which at the very least can leave a scale build up in the galleries which slowly chokes the system, flakes can block radiator cores at the worst corrosion as the coolant and metals react to the minerals................ Deminerlised water is the good stuff, I have always used filtered tank water.....

The Grand is a pain to flush, drained from radiator drain tap with cap off header tank, I ended up lifting the thermostat and pulling the engine hose off, flushing the old coolant out with the hose (rainwater from poly tank) after flushing the rest of the bits, filled it up with tank water , went for blat with windows open and heater on full bore, then drained it all again, then tried to funnel fill the engine via the removed thermostat, gave up and topped it with water, filled the hoses up with straight coolant, tipped the rest in the header tank and topped up with water so I got the 50/50 mix, then went for a run, bit of gurgling/noise at first as I backed out of shed then all good........... so long as you get a 50/50 mix in the system its good, hence why I tipped the balance of the concentrate in then added the water..... the drain tap at bottom of radiator is one of the best I have come across, I actually use it without the fear it will pull out of the bottom ....