The lifespan of a mortar mixer depends on just two things: how much it's used and how well it's maintained. Maintenance involves providing regular care of the key operating components--namely the engine, seals and bearings, the drum, and paddles. ENGINE Every day, check the oil levels in the crankcase and gear box; the oil filter; the air filter; and the tightness of the belts and pulleys. In general, the oil and oil filter should be changed weekly, and the air filter either daily (under dusty conditions) or weekly. Before placing the mixer in storage at the end of the season, replace the oil and drain the gas tank. Another way to extend engine life is to make sure the mixer never runs overloaded, which manufacturers agree is a common problem. SEALS AND BEARINGS At least once a day, check the seals of the main dump bearings on each end of the mixer drum; these seals connect the paddle shaft with the drum and are designed to prevent abrasive materials (sand, cement, mortar) from seeping out of the drum and causing premature paddle-shaft wear. Pillow block bearings, located inside the engine shroud, must be lubricated at weekly intervals, using any grade #1 lithium-based grease. DRUM Proper drum maintenance means preventing mortar from drying and hardening on the inside of the drum and its paddles. PADDLES Mixer drums feature four or six paddles fabricated of metal with rubber wipers bolted on. Check the paddles daily to make sure they are undamaged and positioned correctly. If an individual paddle is damaged, replace it immediately.