You can never give your Mustang's wheel bearings too much lubrication. We suggest high-temperature wheel-bearing grease designed for disc brakes. Massage it into the bearings until they're completely saturated. Bearing cups should be bathed in wheel-bearing grease as well. Apply a thin film on the axle spindle between bearings; you don't want grease between the bearing and axle. The bearings should remain stationary at the axles.