engine flushing oil, good or bad?

[fatboy]

Following a clutch problem last year one of the big washers on the diaphragm got turned into swarf which is now (hopefully ) trapped by the primary and secondary filters.
Obviously I want the best outcome when I drop the oil.
I have heard some claims that flushing oil can cause problems by dissolving crop which can block oilways...
Your thoughts please my learned friends