I have a 2002 Scotts GT2554 garden tractor made by John Deere. This model is now painted green and sold as the John Deere G100. The engine is a 25HP Kohler Command v-twin. The manual calls for 10W-30 or 10W-40 for the temperature range in my area. I plan to use Mobil 1 as soon as the engine reaches 25 Hours. I am thinking of using the 15W-50 in the summer and 10W-30 in Winter. Would the Mobil 1 15W-50 provide better protection for this big air-cooled v-twin during the hot summer months?