Ok mate two things here
I seem to remember that some older skyrunners actually had metal bushes (these need oil)
Most have nylon bushes and there are several silicon sprays that work well and do stop the squeeks and make the bushes last a lot longer
WD40 is a wonderful product that works miracles on some problems but a deffinate no no on nylon
What it does is wash all the lubricant out of any joint it is used on and leaves a thin film of a light lubricant that vapourises after a couple of days leaving the joint to wear away a lot quicker
I use a silicon/ptfe spray grease but I dismantle the joints to get it well into the joint this stuff lasts for hours of use
Another strange but true one is that if you spray water on the joints it will stop them squeeking until it evaporates
but I wouldn't recommend it
What type of spray did you use as some contain other lubricants as well that can make them squeek
Also check that the bushes arn't rotating in the frames and tight on the bearing as that makes them squeek and wears the frames
Jason