Not actually having the car in front of me to check, I'd say it's likely coming from the PS Valve assembly below the Compressor.. a little oil goes a long way in making a mess.. I last added oil to my 90NA PS System, in 2016 when I changed the HP hose.. About 6 weeks ago I just changed the Rack and LP hoses and the Rack was drenched with oil.. But the Reservoir 'Seemed' Full.. There is no really 'Oily Stuff' Above the Rack.. Unless you have a Main Seal Leak on the Crank?..