Yup it's about that time of year again. I never seem to get it done till the snow begins to fly. I usually add stabilizer and have the tank near full. Supposedly cuts down on condensation in the tank. It's always a good idea to fog the carberators to cut down on rust in the cylinders and varnish in the carbs if you don't have injectors. Not a bad Idea to use old spark plugs for this as the plugs take a bath too.
Johnson and evinrude have shrader valves that make it very easy to do the job yourself. I'll be doing my new mercs later after bringing it my new boat back from florida by way of Harkers. I expect the have something similar in regards to fittings for fogging the carbs and cylinders.