I T, you do have a valid point about the book. And, I would say that if you talked to a rep from any oil company you could get the same story about their oils. I just thought, for the price, the book is basically very informative. SO, do you think that the manufacturers recommendations are suspect? I would say, as I have, that if you go by the owners manual you won't go wrong. Do you place any credence in the API specs? If the manufacturer says any oil that meets a certain spec is fine, I think that is sufficient. However, it is good to have a multitude of ideas, and I think TBN is very good for that. In that email, even if he is paid by, or in league with Amsoil, he admits that Rotella is a good oil. I still recommend the book, even if he is biased.