Nissan recommends CV (Constant Velocity) boot inspection every 15,000 miles (12,000 km) or 12 months, whichever comes first, on normal use vehicles. The recommended inspection interval for severe use vehicles is every 7,500 miles (12,000 km) or 6 months, whichever comes first, however, CV boots should be checked for damage each time the oil is changed and any other time the vehicle is raised for service. These boots keep water, grime, dirt and other damaging matter from entering the CV-joints. Any of these could cause early CV-joint failure which can be expensive to repair. Heavy grease thrown around the inside of the front wheel(s) and on the brake caliper/drum can be an indication of a torn boot. Thoroughly check the boots for missing clamps and tears. If the boot is damaged, it should be replaced immediately. Please refer to Drive Train, Automatic Transaxle, Halfshafts, CV-Joint Overhaul for the procedure.