re: OB mechanic opinions.

It isn't necessary. API standards on oil are rigid and it wears very predictably and consistently based on engine operation. Slap some margin on there and you have a system that's 2nd only to having the oil checked. When you're looking at doubling/tripling the status quo on oil change intervals even with the margin you're making a big difference. As long as you put oil meeting the specifications in the manual in your engine, you should trust the light. Putting oil that exceeds the specifications in the manual is likely wasting money unless you get some samples and trend the analysis to see how far you can stretch changes.

Not sure why Toyota is lagging so far behind on this. GM nailed it with their system in the early 2000's.