Do not leave old oil in for the winter

The oil you rode all summer carries soot and moisture. If it stays in the sump for the winter, it works against the engine, not for you.

Change the oil before a long stand, once the season is over. Then clean oil is what sits inside. In spring, check the level before the first start.

Change the filter with the oil if your manual says so. Do not pour in a random oil. The grade is in the manual.