Rick fills the bowl oil with 90 weight gear oil on the berkeley jet drive.. To up 1250 drives twin jet , disc jets hp water , drive doen dj170hp jet dj170hp , twin hp drive , to water jets 1250 drives doen jet up jet disc doen water jets jet j-2380 33 7-12hp direct drive drill press - 354052 jet j-2380 - $24,199.00. Originally posted by cousincletus: just got a new 2002 seadoo gti (2 cyl. rotax) and would like to know what oil to use in the jet drive when i change it at the end of the season (book calls for synthetic but is not very specific)..