Never cut an Osage tree myself, I have cut oaks, cedars, cherry and pines with a Poulan Pro (RIP 2013). My dad bought a $40 yard sale Sthil 025 with a 18" bar, 45cc engine..I had a Sthil dealer tune it up, rebuild the carb..it is a cutting machine! He is an older man and I do all his tree cutting now.. Last year I replaced my dead Poulan Pro with a Sthil 180,32cc with the spring assist starter. Its a small light weight saw. I just used it to cut down a 18" cedar, no problems but the 025 would have been a better choice.