Hello: I started working on cars during high school. Went to work at a Chevy dealership a week after high school, 1971. Still in the auto industry. Do my own service work and maintenance if there are no codes. Former ASE master tech. My 2021 is my 14th GM truck. This is my fifth Duramax (02, 07, 11, 15, 21). I usually drive them 175K to 200K and get another one. I tow a work trailer frequently. I'm interested to see what other people experience with these trucks/engines.