Don't know anything about the Toyota problem and can't say I want to. I don't work on them. However, as a life long mechanic and also a lubricant salesman I can tell you that it's not all the oils fault. I have seen numerous engine designs over the years that are very hard on oil. Even the tried and true GM 5.7L 350 small block had it's problems. At one time I owned a 1988 G30 cube van with this engine and found that deposit's were horrible in this engine around the EGR port in the head even with synthetic oil. The first time I did valve cover gaskets in it I found close to a 1 inch thick solid mass of crud around the EGR port area of the head. It was just prone to happen, it's a hot spot. It's not just Toyota and it's not just the oil used, it's a design flaw.