Yes. You must keep the lube reservoir filled with a water-based lube at all times. Not only does lubricant enhance your experience, but prolongs the life of your device. Oil-based and silicone-based lubricants should NOT be used, as they can damage the sensitive, skin-like material that gives RealTouch its lifelike feel. This would hamper the overall functionality of RealTouch resulting in a less-than-optimal experience.