Welcome to JUST ANSWER small engines, let me try to help you !!
Is oil level above full or is the oil thinned from gasoline in the oil?
Is the crankshaft vent hose from the crankcase to the air inlet housing open and venting?
The oil leaks from the fuel pump when the crankcase pressure is too high.,
What is your engine make and model number?
oil thinned from gas took vent hose of was ok NNN-NN-NNNN31P777 type 0348E1
If oil is thinned from gas, just change the oil and filter if it has one and it should stop leaking. Your engine is single cylinder Briggs, with vent in side of the block, behind the carburetor elbow.