Is there really a difference? Do you really have to put dexos rated oil in a 2015 Tahoe? Why not the delvac hdeo? Does the extended performance 15k mile OCI oil work better for gas engines over delvac 1 esp which diesels run 30k miles ++? I understand they are "just looking out for us" but for real, why not just run HDEO in everything? I know alot of folks that do it and never have had any oil related issues. MY uncles ran Delo 400 that they got for free in their $100k drag cars that made 2500hp. When you think you got it figured out, they make the next best mouse trap....... Heck I know a guy that puts two stroke oil in his diesel fuel at 100:1 ratio because he says it lubricates fuel system components better since they took all the good stuff out of diesel and gasoline Everything I have seemingly found is that its better to have any kind of oil than too little of any of the "good stuff"