best oil and weight for weiland blowers on 575sc

i can tell you that my 8.3L whipple,s came with amzoil manual synchromesh transmission fluid,that,s all i put in any blower,in the old days,i used 75w90 gearlube,it worked well,but the synchromesh fluid is the chit to use.

I've been using the spec Merc HP Gear lube and no problems on my 575's. I've done bearings at about 140 hour intervals and everything has always looked good. 305 hours or so now. I change the oil every 50 hours and I run a 3.5" pulley. My blowers have a "W" on the side, and front and rear reservoirs.