Small Engines (Lawn Mowers, etc.): Stihl FS46 trimmer, octane gasoline, combustion chamber

Question
My Stihl FS46 Trimmer leaks oil through the muffler. Mixture is 2.6 oz stihl oil to 1 gal of 89 octane gasoline for a 50:1 mixture. Had it back to dealer 3 times for this problem - last time carburetor was replaced - still leaks. I use it once or twice a week for 2-5 hours per use. I vary the throttle from full to part depending on toughness of vegetation. Any suggestions? Thank you.

Answer
What you are seeing is unburned fuel and oil.  This will usually come if there is a blockage in the air intake or flooding the engine.  This could be choke that does not disengage all the way or a plug air filter.  It would normally come after the engine has been over choke allot of gas and oil into the combustion chamber, then into the muffler.  A small amount of discharge would be normal.  The best way to clean it out is to run the engine at wide-open throttle bring it up to the full operating temperature and run it for a while.  If it is still doing it.  You could replace the muffler.  There may be a broken baffle inside the muffler.  If the trimmer carburetor cannot be adjusted to run at the recommended rpm,it should be replaced I hope this helps