What do you clean a scope lens with, to get off oil, dirt, and grime? Also what do you do to keep the lens from fogging up in the cold, when you breath ? It is a bushnell 4.5x12x40. I also have a 6x18x50 that doesn't do this near as bad.

I use a special cloth that is made to clean glasses with. I apply very light pressure to keep from scratching the lense. I also have a "scope lens cleaning brush" for lack of better term. Of course the best thing is too keep the lens from getting dirty in the first place by using lense covers. As for as the fogging problem, there are some cleaning fluids that contain some kind of anti fogging agent in them. I have never used them however and don't have any idea what they might do to the coatings on the lenses.