Preventive maintenance is an absolute must,belts,hoses,batteries and cables,tires,brakes,oil,filters replace when needed,just saying dont replace somthing on your truck because it failed on mine.you mentioned fan clutches,had mine replaced under warranty around 90,000mi , the replacement clutch is still on my truck 300,000mi later.still have original injectors,turbo,starter.i believe in preventive maint.but i try to get all the good out of all my parts.