Was reading in another thread that some of Red Line's oils are have more VII (viscosity index improvers)(5w30) than others (10w30) - is this information posted publicly anywhere? Especially if things change, I'd like to keep my eye on it. I don't think these are referring to the base oil? FWIW, learned from Red Line most of their oils have a TBN of 10, and recommended intervals 10k miles to 18k miles Also anecdotes like, the 5w30 flows like a 40wt oil, etc. do the 20wts flow like 30wts? i.e., Rav4 requires 5w30, which Toyota revised to 5w20 - however, some noted it runs better on 5w30 - will Red Line's 5w20 work better here, where it may be more in between? Or can I rely purely on it's viscosity numbers to understand flow - doesn't seem that way, their viscosities seem to line up with most others, or run slightly thicker at most. also anecdotally noted that their 5w30 is on whole all around better than their 10w30 - why? and why does the 10w30 exist then (other reason besides hitting that popular weight)? is the same true for their 5w40, vs their 0w40 or 10w40?