It's that time of year to put things away. I'd say at the very least, do the first two steps. This is a condensed version of Stihl's recommended winter care.
STEP 1: Drain the fuel. Fuel will deteriorate in under 2 months and as it ages, the gasoline becomes corrosive and residue will begin to form inside carburetors and fuel tanks. Prolonged exposure to ethanol is detrimental to elastomers in fuel lines, carburetor diaphragms, oils seals. Ethanol can also cause “phase separation”: formation of layers of fuel, water, ethanol inside your fuel tank. Wash out debris that may be in your fuel tank to prevent it from plugging up the filter. Get rid of leftover fuel in an environmentally responsible manner.
STEP 2: Start and run the engine at idle speed until the engine stops. This step will eliminate any fuel that is left in the fuel system and prevent varnish from forming inside the carburetor. Set the choke and restart the engine to ensure that the fuel system is completely emptied.
STEP 3: Clean and inspect the saw. In order for the engine to cool properly while running, it is important that adequate airflow pass around cylinder fins, so remove any dirt that is built up on the starter housing and around the cylinder fins. Metal parts should have a film of lubricant applied to prevent rust from forming.
STEP 4: Clean and/or replace the sparkplug (let engine cool). Excessive carbon built up on the sparkplug can be removed with a stiff wire brush and the electrode gap can be reset to .020" or 0.5 mm. If you choose to replace the sparkplug, keep in mind that different types of equipment require different types of sparkplugs (heat range, electrode reach and thread size). Before reinstalling the sparkplug, put a couple of drops of 2-cycle oil down the sparkplug hole and gently pull the starter rope to spread the oil around the inside of the cylinder. Reinstall the sparkplug and reconnect the ignition lead.
STEP 5: Clean and/or replace the air filter. Generally speaking, the air filter can be removed and cleaned by lightly tapping the edge of the filter or by using a soft bristle brush to remove any dirt on the surface. Before attempting to remove the air filter, turn the choke shutter on to prevent any dirt from entering the engine. When cleaning the filter, inspect the inside of the air filter housing: any dirt indicates that the air filter should be replaced. Avoid using fuels, solvents or compressed air when cleaning the air filter.
STEP 6: Proper storage. Power equipment should never be stored near a source of heat or ignition, but should be kept dry and out of reach.
