Ummm, need to be cautious with WD-40, as it is a solvent not a lubricant. Great as a short-term fix but not as a long-term solution as it may actually clean out any residual grease or oil in there.
For mechanical parts with no rubber component, then a petroleum-based light grease or oil is just fine. Clean first to get rid of dirt/grit.
For anything with rubber, unless it is synthetic, then a non-petroleum based lubricant is advisable (e.g., silicone grease). Thankfully, most automotive products (except tires) are designed nowadays to live with petroleum oils and not deteriorate on contact.
For sheathed cables, depending on their composition, a light oil works ok. Bicycle shops seem to favor Tri-Flow, but it is a bit too 'runny' (low viscosity) for my liking, but is also useful instead of using WD-40 if you just want to be quick-and-dirty and spray things.
My 2¢, FWIW, although I personally haven't crawled under there to see exactly what all the linkages and cable are that need to be lubricated.
JoeS.
