To correct binding or sticking door lock cylinders and problems in inserting and removing keys, use the correct lubrication with lubricant GM P/N 12346241 or equivalent, do not use penetrating lubricants such as GM P/N 1052949 or WD-40(R) as they wash out If lock cylinders get frozen during winter, apply heat very carefully on the cylinder using a heat gun without damaging the painted surfaces. Use a paper clip or similar object to keep the door shutter open and pressurize air into the cylinders using compressed air via a blow gun attachment. With the shutter door open, put small quantities of the recommended lubrication into the cylinder and work the key into the cylinder several times and with each insertion, wipe away any lubrication from the key.