I had a Shimano crankset with an Octalink bottom bracket that developed a creak this spring. I reinstalled and retorqued a few times but still could not get it to stop. Nothing seemed to work until finally I tried a light coat of oil on the parts and a small amount of silicone rubber caulk on the splines prior to reassembly and torquing. Most of the caulk squeezed out but apparently just enough remained in the small voids between the splines to quiet the creak. So far so good anyway!