Just received Amsoil's lates news letter. They are offering a 10w-40 XL series oil to complete there line up. They mentioned how the lower HT/HS gives you better fuel economy but you don't want it to low because you sacrifice wear. As usual they show the NOAK graph and four ball wear graph, where as usual Mobil 1 and Delvac 1 don't do so well. Delvac 1 had the highest four ball wear scar of .60. Even Delvac 1300 did better. Makes no sense to me.