sit around an watch the tube, but nothing's onchange the channels for an hour or twotwiddle my thumbs just for a biti'm sick of all the same old sh*tin a house with unlocked doorsand i'm f*cking lazy
Find out where it's leaking from and you'll have the answer. It can leak from a hole in the radiator, a cracked or loose hose, water pump gaskets or a worn water pump bearings, heater hoses, heater core, thermostat housing, etc. Stop-leak is the worst idea, and usually causes more problems than it fixes by clogging things up. Its better to just find out where the leak is and have it repaired.
Your boss may have been looking for how well you follow instructions, directions, etc. He may have also been looking for how you multi-task and handle stress. There could be lots of other reasons why he wanted you in the admin role, but, my guess is that he wanted to see how you worked in general.
Just a last point on all this. If you were fired, you should have been given the chance to resign. Today with all the law suits on defamation of character and everything, Companies only put down one word when you leave which is Terminated or Resigned. If your record shows terminated, you will find it very difficult to get another job. Ask to have that changed to resigned. If this is denied, go to the EEOC and claim discrimination. For one word, your boss doesn't want to go through with all that. That's only fair.