If the battery and cable connections are corroded or loose, the car will be harder to start, and in cold weather that means more unburned gasoline diluting the crankcase oil, affecting engine lubrication. Just a light film of corrosion, very hard to see, affects the ability of the battery to accept a charge, so wire-brush the cable and battery terminals at least once a year. Don't forget the other end of the cables, the ground connection(s) to the body and/or engine also should be wire-brushed clean, then tightened, and the positive cable connections should be tight.

Keep the plastic surface of the battery clean. After you've cleaned the terminals, rinse the surface with warm water, wipe down with mild detergent to cut the grease, and rinse again. This will prevent an oily film from collecting dirt, which is conductive and will discharge the battery slightly day and night. Finally, cover all the exposed metal parts of the terminals and cables with grease to prevent further corrosion.