stihl #1

To add to all this:
here in Virginia the gasoline (fuel, petrol) is awful. It has 6 to 10% ethanol added, and winter blend will vapor lock easy, and our weather has been all over the place but mainly way warmer than usual, so it is even worse.
So for me here with this fuel, I use Stihl Ultra full synthetic oil, and add fuel stabilizer as well.
I use a vacuum tank to suck the fuel out of the tank, but leave it in the carb. I do not run the engine out of fuel. It is hard on the piston as it goes lean as it runs out. I have not had to put oil in the cylinder, but it sure won't hurt to do it, especially for a long period of storage. For my saws I actually cut with, I just make sure and cut with them from time to time, at least every 6 months. For the collection saws that I get running but probably will not use regularly, I let them idle out of fuel after sucking out the tank.
I always tune the saw with a tach with the bar and chain installed, to the wide open no-load RPM spec. for the saw and re-tune if I change to a different length bar.
HTH