I don't know about the rest of the manufacturers, but GM 6.6 diesels are 100% guaranteed for 100,000 miles(6.5 diesels guarenteed 120,000 miles). And trust me, diesel has far better resale value in the future when you reach 100,000 miles. I know from experience. But be careful after warranty coverage, I had to have a injector pump replaced on the 6.5 at about 110,000 miles, and the dealer had to eat a $5,500.00 warranty replacement cost.