My 1.0L Geo Metro held 4 quarts. I know the 3.4L Grand Am GTs hold 4.5 quarts, and for that reason I doubt the 1.8L will hold 4.5. They may be able to hold 4.5, but overfilling it is BAD...makes the oil a nice frothy film of nonlubricating bubbles. Only getting 2 quarts back out isn´t good either, are you sure it´s not burning or dripping??
I know my oil is going SOMEWHERE...cause sometimes i pop the hood and it´s bone dry. but i dunno how or why cause my drain plug is tight. hehe (the shop that did my last oil change didn´t snug it down enough...yeah the same shop that did my head rebuild, would you trust them again? I don´t.)