Try the Ol Schlamm Splung to flush it out . That stuff really works.
I had flushed my 225,000mi 240 diesel with horribly stuck rings a number of times with assorted flushes with very little change. Halfway through the first flush treatment with the Ol Schlamm Splung the compression increased so much tha the old worn out starter would no longer crank the engine fast enough to start the thing . After new starter and finishing treatment it went from using a qt oil every 30 miles to a qt every 180, two more flushes brought it up to 480 on a qt, another flush and adding a breather trap from a large truck and is seems to be not using any oil and running great(not bad for a clean car with all new suspension and brakes that I rescued from a junkyard for $425.).
Instructions on the can are only in German , but I have a translation from the manufacturer if you need a copy.
Over the last 25 years of fooling with cars Ive seen lots of products that claim to free up stuck rings , this is the only one I've seen thet really works.