Modern electric coffee grinders use special food-safe lubricants on their burrs and motors to handle thousands of revolutions per minute. Regular oils would contaminate the coffee, so manufacturers use synthetic lubricants certified as GRAS (Generally Recognized as Safe) by food authorities. These lubricants must resist the heat generated during grinding while staying odorless and tasteless. Some premium grinders feature sealed bearings that never need re-lubrication during their lifetime.