If you own a boat or PWC anywhere along the Colorado River corridor — from Lake Havasu City down to Parker and Laughlin, or over toward Bullhead City, Kingman, Blythe, and Yucca — you already know how hard the desert sun and constant lake use can be on your equipment. And if you trailer up to Flagstaff or Prescott for a change of scenery, your engine faces a completely different set of stresses at altitude.