Over the last while whenever I shift I get a sweak from the rear wheel of the bike (from the shifting mechanism somewhere). I can't figure out what the problem is. If I show oil (teflon based) it gets rid of the squweak for a little while, say 40km, the the sqweaky shifint continues. I even tried spraying with WD-40, leaving it for 2 minutes, and then oiling it again (after rubbing off the excess WD-40). This only prolonged the length of time till the sqweak came back (about 80km instead of 40km).
Any ideas of what I can try/do? I am worried that i am doing some permanent damage here.