Putting oil in the cylinder does not do any thing for the crankshaft. You need to fog the motor the last time you run it ( do this when you put the sea foam in it). use a good fogging oil, most dealer can get it for you. If you do not fog the motor it can get condensation in it and that can make the bearing on the crank start to rust.:face-icon-small-hap
Wash it up and let it dry. Grease the chassis/driveline/suspension.Either completely fill the fuel tank or drain it as much as possible.Change the chaincase oil and tension the chain while you are at it. As clutch man stated above-use fogging oil-we fire up the motor and let it warm up to burn off existing condensation, then turn off the fuel valve(if it has one-some do, some don't)-the point is to run the carbs out of fuel for storage. Wile it's running, spray the fogging oil into the carburetors and keep the motor at a high idle to keep it running. Typically 1/2 a can or so of fogging oil will be injested by the motor before it runs out of fuel-that is plenty to completely coat the internals of the motor and the inside of the exhaust (which also rusts like crazy all summer if you don't fog).
You will be standing in a thick cloud of white smoke if you do this properly!
Next, remove the drive belt from the clutches and make sure the clutches are dry. If it has serviceable shocks, get the oil in them changed(same reasons-they WILL have moisture in them and will corrode through the summer if you don't get the moisture out). If possible, get the weight of the sled off the springs and track. If you do all of this you will minimize chances of corrosion and goo build up and the sled will be ready to ride next fall with only a spark plug change after firing up and burning out the fogging oil.
Also, I have seen sea foam turn the viton tips on carburetor inlet needles into a sticky mess causing the inlet needle to stick to the seat and starve the motor for fuel since the bowl couldn't fill...just my .02.
Curt