While it is a neat mental exercise in "what viscosity is best". I think in this case I will recognise that Toyota engineers have more test engines to wear out than I do. I will follow what the company recomends and that is 5w30.
One advantage of using the 5-30 in the Tacoma 4.0
is that's what nearly every UOA used so you can better compare dino v syn or different brand of syn. Looks like all the 5-30 sheared to 56 (edge of 20/30) after 5K while the few 10-30 UOA got 58-59.
