How to fill 1995 gmc Yukon radiator

Just ensure that air or almost all of the air is purged from the coolant system to avoid an air lock. The easiest method is to pull the thermostat out and fill through the rad until you get fluid at the thermostat, then re-install and top up the rad. I run it with the cap off for a bit topping it up until the engine warms up. Once the engine starts warming up put the cap on and let the truck go until the thermostat pops. Shut it off let it cool, top up the rad and fill the reservoir. I have cooked a motor before and recommend that you do not find out how bad air locks can get.