I need to knock a couple high spots down on my jointer bed. I found this thing, and had a bear of a time even figuring out what it was as it was given to me by a friend. Now I just need to know what to use for a lubricant. Mineral spirits, WD-40? And do I let it soak or just spray the bed and have at it, spraying the top frequently to wash away any swarf? Basically a silicon carbide disc, 4" diameter and 1.5" thick. Any advice would be appreciated!