Never saw a water pump on car lubricated by anything other than coolant or sealed bearing. Allow that I have led a sheltered life though. Seems Funny that car is not running well though as leakage is between oil source and coolant. Nothing to do with combustion space. Unless crack or whatever is quite extensive.Also cannot remember any oil/coolant heat exchange device on this model outside of block/ head area. Wonder if you checked head and deck but mostly head for flatness before completing gasket change. When you were flushing /cleaning did you turn heater on to get any trapped oil out of heater system? Or just turn on during drive with new coolant? Own a couple of these and would be pretty disturbing to have happen. People with more experience will probably give much better advice especially about most common failure on these as there are a few 616s around. (hopefully oil pool on ground is from head to block joint area as you might get a break locating the problem) ( if automatic make sure leakage is not between auto transmission cooler and radiator forgot to include this) (one last thing is to go over old gasket you changed for any evidence of failure or poor contact)