Just spraying and cleaning from the outside is probably less than half a job. The air flow and slobber tube tend to blow oil and dirt onto the fins from the 'front' side. If you don't spray cleaner and water from underneath and from the top (under the bed?) you won't get a lot of the grime off. The radiator is a sandwich of radiator, inner cooler, and transmission cooler, probably 8" or more thick. Spray with Simple Green or similar, wait for oil/grease to dissolve, then rinse with spray hose. REPEAT from both front and back of the cooling system. Don't use a power washer, you'll damage the cooling fins.