I like to run them out of fuel, with a heavy dose of Stabil or 2-stroke oil in with the last bit of fuel.
Prior to that, if I'm too lazy to give the underside of the deck a good scraping, just mow through a bunch of leaves. This will blast the underside of the deck clean.
After that I blow the whole machine off with my leaf blower, maybe give stubborn spots a wipe down with a rag and away it goes into the bowels of my garage. I don't do post-season oil changes.
I run mine out of gas. I use Sta-bil all summer, and I have a product from Penzoil that is a stabilizer/winterizer that I start using in the gas come September, so that's usually what I run the mower with when I run it dry. I also wash the underside off, and scrape what I can with a plastic putty knife to not scrape up the surface any more than it is.
After the engine cools, I'll pull the spark plug, squirt a bit of engine oil in the cylinder, put the plug back in (important step as the next step will get oil all over the top of the deck if you forget, and you'll only forget once...), and pull the cord a couple of times to distribute the oil, then try to park the cylinder on the compression stroke and put the mower away.
I change the oil in the spring. The acids thing is on the back of my mind, but I got 14 years out of the last mower and never changed the oil in the fall, and the engine was still going strong when I got rid of it. YMMV, of course.
In the spring, I change the oil, pull the plug and give it a bit more oil, put in a new plug (if needed), put on a new air filter, gas it up with fresh gas with Sta-bil, and let 'er rip.
My mower gets 2 hours use a month during the summer. I treat the gas in my gas can when I fill it up with MMO. I've been doing this for at least 15 years, and have never had the carb off, or had starting problems in the spring. I checked the plug at 10 years, and just cleaned it and put it back in. I do change the oil every other season with what ever is in the garage ,and it runs fine on everything. After 15 years of use, if it should blow up tomorrow, I'd buy another used one for $35 that doesn't run and fix it up.It's a simple machine that you shouldn't obsess over.,,
Maybe look into it. There are acids in used oil that it certainly wouldn't hurt to get rid of.
Actually thats a maybe. If the TBN of the oil is strong, then its dealt with all the acids produced and there are none in the used oil.
But its always good to change the oil once a year and fall seems as good a time as any.
I would run the tank dry. Add some 50:1 2 cycle premix, and let it run a few minutes. Running the tank dry can leave some gas in the carb bowl. The premix will mix with that and it will be fine. Premix has no alcohol.
Last thing might be doing something to prevent mice nests in the air intake. Moth balls work as does a hungry cat?
I change the oil ,lube parts that need lubing and that is it. No Stabil or other snake oils used I don't change parts unless needed.
Sta-bil isn't snake oil. With the ethanol fuel here we MUST use marine sta-bil or the carburetors get nasty. Trust me, I've replaced plenty of them that got so corroded they were no longer usable until I started using and recommending marine sta-bil.
I used the 757 to mow and pulverize leaves for the last time this season yesterday. The oil was changed and sharp blades were put on a couple weeks ago. I pulled it into the shed, shut it off, and it will stay there until I need it in the spring.
Change oil, wash tractor.
Drop the deck and add the snowplow and wheel weights.
Scrape the old grass off the deck, coat the underside with bar oil, touchup paint scratches on the top of the deck.
Grease bearings and bushings.
Fluid Film or undercoat touchup on the tractor.
I just put my Cub-Cadet away for the Winter. I had changed the oil not to long back. I take the deck off for easier storage, greasing, and springtime blade sharpening.
I don't run engines dry anymore, always leaves a little residual gas. I use. Non-ethanol fuel during season. I store with the tank full of 100 low lead aviation fuel, run into the carb. I just run it through in the Spring.
Up until this year I have never done any winter maintenance for the push mowers. The 2 2 stroke LB's were ran for about 15 minutes at full throttle then the fuel lines were shut off so they ran out of fuel inside the carb.
The 4 stroke mowers still didn't receive any treatment and will most likely fire right up next spring with 1 or 2 pulls. Everything here gets an oil change in the spring.
I pulled my rider into the shed, filled the tank, took the battery inside, and called it a season. The gas that's been in the rider since day one is 87 E10 (no E0 available around me) dosed with red Sta-Bil. Runs fine on it. We'll see how it does in the spring.
If my other tasks allow me to be fast and efficient, I hope to pull the blade to sharpen and balance, change the oil, and clean the air filter tomorrow.
Any concerns with me running the engine without the blade attached? I may wait on sharpening and balancing the blade in the interest of other chores.
It will not hurt the engine to run it without the blade, if it will start, and if it doesn't jerk the rope right out of your hand. Seems some work better than others without a blade. Also they generally won't idle well. Remember, the engines that don't have blades,like tillers riders, etc. all have cast iron flywheels, and those with blades have lightweight flywheels. (generally)
Run the gas out, change oil while warm, squirt some oil in the plug hole and put the old plug back in before pulling rope a few times stopping on the compression stroke(valves will be closed).If it still has points, the points will be closed at this time and will not corrode up during storage. Put a new plug in the spring...no need to get a new plug coated with that oil. Prior to all this I like to run the mower thru a small pile of leave to scrub the underside of the deck clean. Otherwise, hose off the underside while changing oil.Happy mowing in the spring.