what oil to use

NO BUT MOST diesel oils also met SM spec for gas engines

There is not much difference in the additive levels
between CI and CJ HDEOs.

Ted, what part of the Allpar article do you believe has not been updated? The second paragrapgh starts out mentioning SM. API SM rating was introduced in 2004 and is NOT a diesel oil rating.

Mentioning SM and GF4 in the same sentance much less saying something like "SM/GF4" is misleading and inaccurate. API and ILSAC are two different, unrelated organizations. Their ratings are not similar at all and certainly not interchangeable.