Lots of places can leak oil. As jay_nar suggested it could be the valve cover. If it is an 85, I don't think muranos were made until the 2000s though, then you might have cork valve cover gaskets which are prone to leaking and is a real easy fix. The front engine seal or oil pan gasket would be my next guess.
It could be a valve cover leak, or it could be an oil pan gasket leak, or a crankshaft seal leak, or an oil pressure relief valve leak, or an external oil pressure regulator leak, or an oil cooler or cooler line leak, or an oil pan plug crush washer leak, or an oil filter leak, or a PCV valve leak, etc.. I doubt your car has all of the aforementioned parts, but my point is that there are many possible sources of the leak, so it's going to be really hard to tell you what's leaking without being able to inspect the car. Try finding the source of the leak. You shouldn't even have to lift your car to look under it. If you don't know what you're looking at under there, try looking at a service manual, or looking up part numbers, or uploading pics to this thread.