I'm a new mechanic, kind of fell into it so I'm still quit ignorant that being said i maintain about 16 Stihl BR 600's we use them summer and winter. I was putting them in winter mode earlier but I don't completely understand what this accomplishes. More accurately it seems counter intuitive to me. It seems like winter mode allows more air into the machine and summer mode allows less air in. I would think you would want the opposite, although my observation could be wrong. Could anyone explain to me what the winter / summer mode accomplishes? Thank you.