If you fish year round then changing the dope in the lower unit should be changed each fall (just in case the seal leaked a little letting water into the foot). If youyre garaging your boat until springtime then lower your motor all the way down and remove the two screws and let the dope drain out. Be sure not to loose the screws before next spring when you add new dope. Late fall is alwo a good time to grease your wheel bearings too. And as mentioned....NEVER leave you motor tilted up as to where it can trap water from rain or snow during the winter months.