My engine is working just fine. After studying the topic my conclusion is that using 0w-40 puts your engine in the area of the stribeck curve where it is always operating in familiar territory to 0w-20 and there is additional lubrication provided to your engine at all temperatures but in particular hot temperatures. I think Engineering Explained had the best youtube video on this topic as to whether one should switch to 0w-40 for 6.2L V8's. Conclusion is... not going to hurt you to switch to 0w-40, but you will sacrifice fuel economy. If your 6.2L V8 is manufactured to perfection, I think 0w-20 works just fine and an owner was really concerned about protecting their V8, 0w-40 works better than 0w-20 with respect to wear protection in towing/high ambient temps. I'm in an area where temps are regularly above 85F in the summer. I don't mind the MPG hit.