[ctviggen]

I currently have a snow blower, lawn mower, power sprayer, air blower, and weed whacker.  The air blower and weed whacker use oiled gas (i.e., gas with a small amount of oil in them).  The others use strictly gas.  What I'd like to know is what I'm supposed to be doing to these each year.  For instance, this year, I replaced the spark plug and the oil in the snow blower.  I'm thinking of doing the same in every other small engine.  Is there anything else I should be doing (like an air filter?).  What about adding some type of gas treatment for deposit removal?  I typically use gas that's been treated with gas treatment.  Is this beneficial or only beneficial when "retiring" the engine for the year?  (As I'm about to do with the snow blower.) 

Speaking of retiring the engine, do you drain the gas and oil, or fill the tank with treated gas (and run the engine a bit to ensure the gas is through the engine)? 

[Berndt]

I used to be a service manager at a yamaha/honda/john deere dealer.
The new fuel formulations will turn into long chain polymers in 2~3 months, ie. gunk.
I would try to fill up with fuel that has been stabilized before storage with a metal fuel tank.
With a plastic fuel tank I would drain the fuel before storage. Try to avoid fuel with alcohol as it is hydroscopic.
Also secure the fuel petcock if the tank is full and run the carb dry for storage.
I normally keep an extra plug for every piece of equipment in my inventory and change as needed, or, when starting becomes hard.
Along those lines I would suggest annual airfilter inspection, depending on your conditions. Snow blowers aren't subjected to much dust, only wet which can swell a paper filter. Inspection will reveal what the engine wants.
It is recommended to change the oil before storage and again before running the motor when putting it back into service, some people go as far as to fill the crankcase to the brim before storage for moisture protection but that raises hell if you forget to drain the oil before restart.
Call me if you have any questions, I walk my Father through this each year.
Bill