What about slight tolerance changes to an engine that previously spec'd 5w30 but now specs 0w20? For example, the Toyota Tundra 5.7 V8. It used to spec 5w30, but now 0w20, and as some people have shown, the owners manual for that engine in other countries still shows 5w30.
Could tolerances have been modified in the engine for models that came after the spec changed to 0w20? I watched an interview with Mike Sweers, the engineer for the Tundra, a few years ago, and in it he states that they often make small changes to the 5.7 each year if needed. Made me think they changed the tolerances slightly, or something else in the engine to accommodate the 0w20 as the spec'd oil.
Is that possible?