Ulmer Racing has run XP2 in Apex & FX Nytro models starting in the fall of 2007. We have even run XP0 in racing applications with no oil burning. We contacted them with the engine tolerances Yamaha runs and they sent us both XP0 and XP2. The only down fall to the Joe Gibbs oil is that the "corrosion resistance" is not as high as Yamalube, so we recommend changing the oil in the spring time when your season is over. Joe Gibbs now has a new MX1 oil that I would like to try as well, but haven't yet.
How many miles on the sled? How was the sled broken in?