I've used M1 5W-30 in my Tacoma since its first oil change. It's never had anything else in it, and I switched to the EP at around 75,000 miles. 221,000 miles now and no oil consumption over my 10,000 mile OCIs. Never had the check engine light on.
I've also used the 75W-90 in the diff since 100K with no issues.
Incidentally, I use the Toyota WS transmission fluid (I've done a total tranny fluid swap twice - first at 100K, then again at 200K), and ive heard it's an Exxon-Mobil product. Never a single transmission problem either.