Many mowers use SAE 30 auto-engine oil. Exhaust fans in bathrooms and kitchens often work hardest in hot weather. To service a fan, turn off the electrical power, remove the grille and pull the electrical plug from the outlet inside the housing. Many fans can be removed from their housings by loosening a few screws and twisting the fans so they can be pulled over the screw heads. Take the fan outdoors for cleaning.
Clean fan blades with a cloth moistened with detergent solution.
Be careful not to get any water in the motor. Clean the motor with an old paint brush or a soft, dry cloth. Check the motor to see whether it needs to be lubricated. Motors that require oil have a small oil port, sometimes with a cap, where the fan shaft enters the motor housing. Put a few drops of electric-motor oil or light machine oil into the port.