The Stihl 600 and the Shindy 854 are both 4 strokes that run on 2 stroke fuel mix. You only have to adjust the valves one time. Stihl recommends doing it after the first 139 hours of use (or as needed either before or after, and maybe not ever depending on how it is running), and I don't recall off the top of my head what the time frame is for the Shindy, but it's something similar I believe, and it is a one time deal too. By not having an oil sump, they save weight and size. Both are much more fuel efficient than the 2 strokes that are out. My 600 will easily go twice as far on the same amount of fuel as my 570, and both have 65cc engines. I gotta say though, that I love this 570, and the more use it, the better I like it. It is also getting stronger as time goes by too.