Oil & Funnel

Some locks may grow rusty with age and disuse, and be harder to pick than new locks of the same quality of make would be. Seasoned thieves know only too well that the locks of doors in dungeons are all too often of this sort. The DM may apply modifiers (-5,-10, etc.) to the open locks chance for such doors as he sees fit. rusted and even fairly dirty locks may have a little light oil applied to their insides, usually with the use of a long-necked funnel (and maybe with a short length of rubbery tubing on the end of that). The negative modifier may itself be negated, in whole or in part, by such lubrication. It takes 1 round to apply the oil and 5-10 (d6+4) rounds for the oil to have its effect on the mechanism.

Of course, using oil to lubricate a lock helps the thief to open it silently. If the DM wants to make a silent movement check for lock-picking, it should be made at +10 if oil is used. Oil is also useful when it comes to rusty door hinges in this context.