I've noticed that my Turf Tracer hp has the mobil one oil from the hydro on top of the tank. I assume it is comming out the breather hole in the cap. After cleaning it off the tank and using the machine for a day it is once again wet on top of the tank. the machine runs great and the hydro system works great. My dealer says this is quite common, but I don't think my other TThp does this. This machine has 120hrs on it now.