I have a friend who wants to split a case of oil with me. I use the 5W-30 (ASL) and he wants the 10W-30. Is there any advantage to the 10W-30 over the 5W-30? From what I have seen of the oil data on the web site, there isn't much if any advantage to the 10W-30 or am I missing something. I also have a good UOA in my Vette with the 5W-30. Second question, I have been reading here lately of a possible reformulation of Amsoil products and that the TBN values are dropping very quickly. Is that all products, or only the Series 2000 0W-30?