The 2-stroke oil won't stop your mower from starting - unless there's LOADS of it. A normal 2-stroke mix will just make the engine smoke a little - in fact I use 50:1 2-stroke mix in ALL my equipment. It's safe in that I never put neat petrol in the 2-stroke equipment, and the only cost is reduced spark plug life in the mowers.
If you put a real 'gloopy' mix in, you will have to remove the carburetter bowl, and drain it. You may need to blow through the jets with carb cleaner. That should be all that's needed.
phil_saunders(a)bigfoot.com
Phil Saunders, July 2009
