I wouldn't put any oil on it. Over time the wheels get less and less clicky. And eventually won't click at all. (At least that has been my experience dealing with the few hundred phones we have in this division of the company)
Prior: BES: 7510, 7520, 7290, 7230, 7130, 8220 (No Data Plan), Droid Eris
Post your question on the forum, don't PM me.