For motors with fixed endbells, I poke the motor's shaft through a plastic sandwich bag, and put a slight bit of electric tape around the bag on the shaft to keep the metal shavings away from the motor and the bearings.
SH Z-Car, Custom Crawler, 8s Savage, 12s XTM XLB 1/7 buggy, 4wd 4-link rear/IFS Pro4 truck, Custom Hyper 10 Short Course, Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz