Hi,
If you are unsure of the signs, that differentiate excess fuel ,ie flooding carb, from leaking crank seals.
remove crankcase drain screw, drain fluid , replace crankcase drain screw, remove Carb from intake manifold , seal inlet, recheck crankcase drain after a couple of weeks,
when you say "engine oil" do you mean transmission fluid, if you suspect a transmission fluid leaking into crankcase thru case joins or past crank seals , Drain transmission completely refil with Auto transmission fluid, TQF, the red one, with no carb fitted , and recheck crankcase drain after a couple of weeks ,
you could do it the other way by draining the the transmission and leave the carb connected,
cheers
ps dont use "TQF" for transmission fluid in a CZ