don't worry about it so much, bmw's are solidly built and i doubt that there is anything wrong with it mechanically. tho it would not hurt to get it checked out. the oil dripping from under the car may be from several things, could be a simple o-ring that needs to be replaced from the oil pan. or some other fluid. at 180K there are going to be things that need to be replaced obviously. go to the mechanic and get get it checked, things to look for on the e36 are bad water pump(because it came with plasitc impeller) and rear shocks mounts. other that if the prevous owner was halfway careful with maintenance then it should be no problem. cheer up u have a bimmer now enjoy it.