Based on previous DRN threads, one could make a huge generalization that while 100:1 may not seize, it may also add to increased wear. Most synthetic oil guys on DRN go with 20:1 to 40:1 IMO. You will achieve much greater performance gains by fine tuning jetting, race fuel, or aftermarket parts, long before you can measure a performance gain by brand of oil. As far as engine life is concerned, how can you rationalize the miniscule amounts of lubrication at 100:1 that occur in the fuel of a 2-stroke engine? I recomend synthetic oil by Mobil, Yamaha, or Redline at 38:1 for trail riding.