I had it installed in my GMC Sierra DuraMax Diesel after a triple flush. The Amsoil coolant meets all ASTM specifications for heavy duty diesel engine use. This engine also has a coolant bypass filter installed. Because any cooling system failure would be expensive, I decided to use the Amsoil propylene glycol product. This coolant is rated for extended service life, 7 years or 250,000 miles, however I use the test strips and will send a sample for analysis annually, or to back up a questionable test strip indication. The lower toxicity is also a factor. The cost of these premium fluids (Amsoil lubes and coolant) is not a factor for me, especially when replacing the coolant pump is a $2,000 job, and a replacement engine costs $7,000 plus labor. I plan to keep the truck a minimum of ten years. For the average motorist, with a shorter turn over a cheaper coolant may make just as much sense, providing it is changed every two years.