your om617 could have more than 150k on it.. have you had a carfax ran on it.. the odometers are known to fail. any valve adjustment lately? all oil cooler lines tight to spec, same with oil filter housing and gaskets..

to find where the oil is coming from degreases the engine extensively.. it will help. i thought my oil pan was leaking .. i degreased.. nopre just a pinched wire on the valve cover gasket..