First the easy one -- I have heard that most if not all '92's (in addition to all '93's) have ABS.

Next the hard one, about the oil. Are you sure it's oil? Antifreeze (coolant) can be "oily", but there's that giveaway smell that you didn't mention. Lots of coolant in the passenger compartment (heater hoses, valves, heater core, etc.) to potentially leak. In contrast, there's no real reason for there to be oil in the passenger compartment.

One remote possibility: do you, by any chance, have an aftermarket, mechanical oil pressure gauge that (maybe a previos owner) installed? These have a oil line that does directly to the gauge -- the line, at the gauge, could leak! Happens in older Mercedes cars! And one reason why electronic pressure gauges are so much better.
Okay, I did say it was a "remote" possibility.