I have AMSOIL in my 2017 Sierra Denali Ultimate, 6.2L. Have used it for over 25 yrs. Ran it in my 2012 Denali and every GM vehicle dating back to the 1980's. I also use it in my 2016 Polaris RZR 900 and my 2017 John Deere X738 tractor. I change oil once a year which equates to about 15,000 miles. I have NEVER changed oil sooner than that Only the best in my vehicles, I never cheapen out. I saved all whole lots of money over the years on needless oil changes.
AMSOIL has been producing synthetic oil since 1972. It could arguably be said they started it all. Everyone thinks Mobil 1 was first but they came circa 1974. AMSOIL is made in the USA, Superior, Wisconsin.
This is what I use, 100% synthetic ►