What do I need to do when changing from conventional non food grade to food grade lubricant?
Change over from mineral oil to food grade has to be done in the same way as any switch from one product to another. Keeping in mind food safety and contamination risks, contamination with the former oil quality must be kept as low as possible. Thus the old oil should be removed and the equipment cleaned or flushed, maybe more than once, with the new oil before final filling.
