Sliding door lubrication

HI all
Just wondering if the rollers and pivots on the sliding door on my Symbol should from time to time have a spot of lubrication. 
I have read that the track should not be lubricate because it can cause the nylon wheels to skid and cause flat spots.
The door rollers may have sealed bearings in which case all is well but if plain bearings will need something to keep them
running smoothly. 
If they should have some lubrication what would be the best to use.
Malc.

Try a spray can of silicone lubrication which is suitable for plastics and no plastics. Good for all moving parts like hinges and latches, etc.

I cleaned the muck and grit out of the bottom track on my Symphony and used a little spray grease on the bottom track and middle runner and it was so much smoother and quieter.

I think a thick grease might stop the rollers but a light spray lubricant subtley applied (wipe off any excess) should be ok.

Didn't touch the top roller as it's nearly non existant and is on my to do list!!

Thank you for your help with lubrication of the side door rollers.
Malc.