[quote="itchyfeet"]you might expect poor running if your plug was loose but oil coming out is ususlly a sign of oil in the combustion chamber, it should not be there in any significant quantity.
OK the engine might be past it's best and if the plug wasn't firing for some reason then the full piston seal at the top rings may not be be achieved and any oil present maybe pushed up the bore and would not be burnt and could find its way up the loose plug threads. The oil scraper ring/s probably work both ways. Too much coincidence at play here maybe but worth a thought... I am often surprised how little oil an engine can burn with considerable barrel wear.
I remember in the good old days - spit - pouring Redex down the carb at full throttle to clear stuck/gummed in piston rings.
CS
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