Lubricate a Lock Using Graphite From a Pencil
How to lubricate entry doors and what to use : Lubricate A Lock Using Graphite From A Pencil
Quote from Article entitled How to lubricate entry doors and what to use:
Cylinder locks require only oiling a latch. For this purpose, one usually uses WD40, but it dissolves fast, and thus has to be systematically renewed. This substance has a high capacity for water repellency, and effectively protects parts from corrosion. Silicone spray is also good for oiling lock cylinders.
The full version of the article can be found here.