Oil ring cleaner
 

Car is using major oil, and would like to try cleaning the oil rings on the pistons, in-situ. Can anyone recommend some fuel/oil additive that does this?

Thanks!

Dear Vronsky,
You could use a fueladditif from Marly if available in your country.
But as these products are very effecif it is NOT impossible that
some trash could do (a lot of) damage to valves and valve seats etc.
Guess how I learned about this...
So far better and wiser is to find a specialist's (a real one!) advice.
Maybe it is as simple as leaking valve stem seals, VERY common on the
becoming older, hydraulic adjusted valves in all the W124 engines.
Good luck and keep us informed!
Danny.

With todays oils, I seriously doubt that your rings are stuck such that a chemical would help them. As the previous poster indicated, it is more likely worn valve guides. Occasionally replacing the seals will help significantly.

If you still insist on using a chemical to free the rings, I would mix just a little solvent(diesel fuel would do, about 20%) with some automatic transmission fluid. Remove all the spark plugs and fill the cylinders with this concection through the spark plug holes.

Let it set overnight and the next morning, turn over the engine with the starter to blow the bulk of this oil out of the cylinders. Then put the spark plugs back in and drive it until it is at operating temperature(about 25 Kilometers) then drain the oil and change the filter.

Many years ago this was occasionally necessary because the oils of the day did not have the additive packages that we have today.

Good luck,