93 Sl 600.
 

Have oil leakage at engine front on lower radiator hose and pan. Mechanic not certain of source as yet. 27k miles. What is the most common source ?. Not pooling on garage floor as yet. Benign neglect approach appeals to me.

Hopefully it's the oil pan gasket and not the crankshaft seal. All the accessories on the front of the motor have to come off to get that off.

If it's leaking ON the pan, then it could even be coming from above e.g. the valve covers.

Cleaning/degreasing the area and letting it sit will help you pinpoint the problem. Your mechanic might add a dye to oil to find the origin as well....