I'am the mechanic who replaced timing chain on 1994 mercedes benz s500 smoke from tail pipe smells like oil

The smoke coming out of your exhaust is most likely oil being burned through your engine. The oil gets into the cylinder by a few ways. The first way is for the oil to get by the oil control rings of the pistons. The engine’s pistons would have to be removed and the rings replaced on each piston. Also, oil getting by the valve seals on the valves can cause the smell, which indicate the valve guides are worn. This would mean the heads have to be removed and rebuilt. The last cause is the engine has massive amounts of sludge and is clogging the oil entries. This would lead to the oil being sucked into the intake from lack of oil changes. All of these problems will require the engine to be checked and major repairs have to be done to fix it. I would try an oil engine flush first