i've read here in tsikot sometime ago that the colorado duramax was designed with a service life of 290,000 miles. I thought after that mileage the vehicle will become useless. but this is not so after reading a new book "Diesel Engine System Design" by Q. Xin. If this is true (290,000 miles), what actually it means is that the colorado duramax is classified as a "heavy duty vehicle" by The American Automotive Manufacturers Association (AAMA). A workhorse vehicle in that case.