Creaking dropouts
 

On my older Specialized Roubaix (2008 Comp), the rear dropouts are apparently bolted to the seat stays from the wheel side with large headed bolts with a 4mm hex head, then painted over. Tracking down a mysterious creaking noise, I finally traced it to slight movement at the dropout/seatstay joint. I could feel it working (and hear the creak) by pushing side to side at the top of the rear wheel. I cleaned out the paint from the hex head and was able to tighten each of them, very slightly, maybe 1/32 of a turn. I didn't want to push too hard.

This seemed to work, my noise and the slight movement are gone. Turning the bolts broke the paint seal. Should I apply some paint or something else to lock these in place? I kinda doubt they will loosen on their own, but stranger things have happened. Has anyone messed with these fasteners before?

The bike is 11 years old at this point. I've owned it for 5-1/2 of those years and have put about 30K miles on it, I don't know how many miles were on it when I bought it. So it doesn't seem surprising that these joints might be working a bit by now. There is no evidence of any damage or other trauma there, just this slight play.