one thing to think about is your boat i see you run a slt. what works in a tunnel may not be what you need in a slt.gear oil is for differant things cooling,lubrcation & a buffer between surfaces.i have not seen you guys run but if your on & off the the gas a lot or jumping out of the warter a lot you may not what to go with the 0 weight lube the 90 will be more of a buffer.the manual calls for omc ultra-hpf. i run the same stuff mark does in sst 60 put i have to say if i was racing a tri haul or a v bottom boat i would run the hpf 90.i do pin my carrier. the big problem i have is keeping the case sealed that is why i pinned it, doesnt seem to help. keep an eye out for leaks.maybe sam la can chime in on this he would know.buy the way you need to run 92 aki (96 ron ) fuel. good luck.