if its a honda then it could only be leaking from valve cover, vtec solenoid, dist. oring, rear main seal, oil pan, seals at the front of the engine(including balance shaft), pcv canister at the back of the block and oil filter housing. you will have to trace the residue. if the residue is too much, then clean, drive and try to retrace. pretty much most engines will work like that. you have the front(timing belt side), rear(tranny side), top(valve covers, misc) and backside(oil coolers or filter housings). all have seals. some are easy to get to, but front and rear are the most time consuming. good luck.