1992 Acura Integra Anti Freeze disappearing

1992 Acura Integra Automatic A lot miles

I am asking this for my son so I'm not sure about some of the info. Last week the fan would not shut off after driving. My neighbor looked at it and the plastic holder that holds anti freeze was very, very low (not much in it) and the radiator was empty. He put anti freeze in it and it cooled right down. On Sunday his car wouldn't start and he had a couple things wrong with it. He said that the anti freeze was empty from when we filled it on Thursday. He got it filled and when he picked the car up today from getting the problem fixed for the car not starting they told him to just watch the antifreeze level. There were no leaks on the driveway or where his car was. It seems to me that if it was filled on Thuursday and just about empty on Sunday something is wrong. So I'm trying to find out what so I have a little bit of an idea. He does have some oil leaking out but not much. Any ideas for me and expense of repair that might be needed?