I can tell you this, after seeing my injectors and what it looks like inside when they go bad, two stroke oil only masks the inevitable for a little bit. I was a regular user of it (1 quart every fill up) when injectors were last replaced and even with balance rates no nore than +-2 before the rods bent, the injectors were shot. They had 65k on them. The oil only fills the voids inside from pitting/cutting from the fuel so it seems as though its helping but the damage has already been done. Ill still run it as the motor is quiter and i dont see it hurting one thing but its not preventing anything either. Guy at socal did the testing on them and these injectors were also pre-chrome ball and seat. The chrome will help way more than the oil IMOP. Thats just for us LB7 guys
For your lbz, its probably time to take it out and send it off to be tested. That will tell you way more than any of can tell you. If all 8 cost 400-500 bucks to be tested, i doubt it would be much more than 50 bucks for a single. Could be wrong though.