Ouch,
When the linear rail bearings run out of lubricant this can happen, I have put super-lube in some with a syringe when lacking a suitable set of grease nipples and grease gun to lube them with.
I would put some real grease in rather than just oil as the oil will run out pretty quickly, avoid anything with molybdenum disuphide or graphite as these are not lubricants but are abrasives in this application.
These are the HiWin instructions on how to lube up a linear rail bearing