If it is a KRL then it more than likely has roller bearings. The best thing to do is remove the drawers, clean the rollers/bearings and lube with a teflon aerosol such as TriFlo, Zep 45 or Royal Purple's MaxFilm spray on lubricant.
If they are a friction slide drawer it is more than likely a KRA and I would still remove the drawers and clean the tracks/grooves. I would then spray them with something such as Zep 2000 which is an aerosol that thickens up to a grease like substance as the carrier evaporates. Some of the guys that I work with have used a product called Grease Monkey, Grease in a Can. It looks quite similar to the Zep 2000 that I have used. Use it sparingly as you want it to lubricate and reduce friction, not collect dirt and grime.
My son just did his KRA over the weekend and it is much better than it was before.
Mike.