1990 Deville

i have a oil leak on driver side and i dont know where it is coming from.

Welcome to AF. Well without checking it out neither do we. Clean the area and try and see where it starts or put oil leak tracer dye in the engine for a more precise diagnosis.

On the 4.X engines the leak is often up at the oil filter adapter. Remove the air filter assembly so you can get a good look. Sometimes just tightening the fittings is all that is required. BTDT.