Wasn't it the introduction of catalytic converters that forced lower levels of zinc in gas car oils?
This is a common method of "proposing ones point of view" not as a fact, but as his perspective.
Before that, oils were optimized for best protection. Now they are compromised, having to accommodate the catalytic converters. Diesel and race engines don't have cat converters so oil types for them is preferred. That's how I see it.
This is where Schnell intimates that he "may be mistaken or misled" but has this position based upon his experience, understand in or interpretation.
English spoken in the US is a tricky, and heavily nuanced language. And Schnell, if I recall correctly, is an educator so his mastery of tone and structure is used in subtle ways to imply he's comfortable with a topic, but in no way professing himself to be "the master". It's a very polite method of opening dialogue, and he's done so brilliantly.
Hope that is helpful to you.
