so, should I flush maggie? the oils a bit black, and it's been 12K since the last one (should I be doing it every 6

I use halfrauds green classic oil and decent filters, what're the thoughts on flushing, and has anyone done it regularly with no (or some) good (or bad) effects?
Andrew
1098 standard gold seal with 50-60K (ish) on the clock (because I'm not sure when the PO fitted the engine.
Andrew