I disassemble freewheels and clean them. I always use either an empty 2 or 5 gallon plastic paint bucket to catch everything as it falls apart.
Every time I have flushed then oiled, they still feel and sound gritty.
__________________
1971 Paramount P-13 Chrome
1973 Paramount P-15 Opaque Blue
1974 Raleigh Professional Blue Mink
1991 Waterford Paramount
Holland Titanium Dura Ace Group
Holland Titanium Ultegra Triple Group