Single axle trailer riding an 18 foot bass boat. Replaced axle about 5 years back due to minor wreck. Went with a good heavy duty one. All my spring shackles and pins appear tight, no play and working properly. Problem is they squeak.....not real bad but squeak, squeak as you back up to launch. Not brakes because don't have them. Would you or would you not lubricate them and if so with what? Minor problem but help and suggestions appreciated!