Yes this is an old post but evidently there are some readers still looking at it. I R1. Dave. B has a good flush idea with the 50/50 oil paraffin mix. I have my own way that I have been using for more years than I would like to remember. Without problem I might add. I use 1 gal. diesel and 1 Qt transmission fluid in the crankcase. Start by draining the oil, remove the filter and empty the oil out of it. replace the old filter and fill the crankcase with the solution. Run the engine at idle for about 15 minutes. Wait for the engine to cool, drain the the oil, remove and discard the the filter. Refill crankcase with new oil and filter and enjoy an engine with a smile on its face. Happy engines last longer.
WARNING: DO NOT UNDER ANY CIRCUMSTANCES SUBSTITUTE GASOLINE OR ANY OTHER FLUID THAT HAS A LOW FLASH POINT!. nuff said.