One tank of oil per tank of gas. If you don't fill it that often, then you have a problem. To check oiling, rev the saw out of the cut and see if it sprays oil. Use a piece of cardboard or something to check this. The chain will sling oil off at the tip and should splatter a decent, but not excessive, amount of oil. Just takes a second or two to check, no need to rev it long.
With the saw off, check to see how the chain moves on the bar. If it is too tight, hangs, or you have trouble moving it, figure out why. With the saw off and the brake off, you should be able to easily turn the chain on the bar.
The most common cause of excess heat is probably a dull chain. Chains dull quickly and need to be sharpened freuqently, depending on conditions. If you cut all day on one chain without sharpening it, you are probalby cutting with a dull chain. I like to sharpen every other tank or so, depending what I am cutting. When cutting dirty wood, use a semi-chisel chain and stay out of the ground. Don't cut all the way through the log, as there is a good chance of hitting the ground that way.
