Good luck freeing the stuck oil control rings.
My experience told me that once the oil control rings are stuck (jammed by carboneacious deposits) and the oil drain holes clogged up, nothing can be done in-situ to break the oil control rings free at that stage.
Not with soaking it with UCL like mysterous elixir, not kreen, not auto-rx, not solvent (coz it will lead to serious cylinder wall "washdown"), etc.
The only proper way is to overhaul the engine with fresh new pistons (oftentimes, a revised version of piston should be available by then), new ring sets, valve seats and valves ground, all seals,valve guides, etc. refreshed and checked, cylinders resurfaced, etc. (list goes on and on), before you can get that automobile on the road again.
Nursing a stuck oil control ring engines will eventually get to the cat con, no matter how meticulous you have been with using low phosphorus oil, etc. The oil itself will speed up the rendition of the catalyst failure.
Q.