So you're going to drain over a gallon of coolant onto their parking lot! ? With the car cold, engine off, remove the radiator cap slowly by pushing down on it as you turn it. Then, get under the front bumper, locate the drain petcock and with a pair of pliers, unscrew it. Have a drain pan under it that holds at least 2 gallons. Once its just dripping close the petcock and add new coolant. Then start the car and have a gallon of water at the ready. Leave the rad. cap off till the car comes up to temperature, then you'll see the coolant level drop. Add the water till its full again. To the very top of the radiator. Then quickly reinstall the new cap you bought when you bought the coolant. I don't recommend any "tabs" be added. They were recommended when the car was still under warranty to stop any chance of porosity leaks in the aluminum block. If its not leaking now, it never will! I can't figure what "tool" you'll need to rent?