Chainsaws run at full load most of the time. This why it is important to adjust the mixture screws any time you change fuel mixtures, altitudes, climates, etc.
A little four stroking at max rpm unloaded is usually good, keeps the mixture rich enough at load in the cut.
Lucas fuel additive is oily. Nothing wrong with that. Don't reduce the manufacturer's recommended oil ratio. I would not add more than 1/2 ounce of Lucas per gallon of fuel. On an engine with a lot of hours, it may give a little better ring seal.
Here is some more info: