its probably the front crank seal where crankshaft come out of the front of the engine. they get hard with age and then start leaking, to replace it you can to take the timing belt cover and timing belt off and remove lower crank gear to replace it. the oil pump is right behind the seal so after it gets hard it stops sealing and dripping oil out. and might as well replace the front cam seal at the same time. also depending on the mileage or if timing belt has been oil contaminated you should also replace it at the same time