i just changed the lower unit gear lube oil and put back the small screw and when tightening it. it just kept turning never tightening up like it was striped is it suppose do that. no fluid is coming out. also when i change it little fluid came out but it was not milky
I'm guessing a merc 7.5 or 9.8.... If the screw keeps turning, then yes, it's stripped. Time for a bigger screw, or a helicoil... Or a replacement gearbox housing....
Helicoil is a thread replacement... http://www.helicoil.in/helicoil.htm
To helicoil that hole is not going to be easy... I would drain the oil and strip the box, to ensure no bits of ali were left in the box...