As for "high pressure additives", combistion chamber pressure isn't what is being refered to in this regard, but rather the fact that your motorcycle has an integrated transmission where the oil is getting constantly sheared down at high pressure between gears, which is a considerably different environment than a diesel engine.
Keep in mind that new "diesels" now have catalytic converters, and that "diesel" oils have gotten a downgrade in their additive package (zinc and phosphorous) for that reason....just like cars got a downgrade some years ago! The point here is that some VOA that looked good for your favorite diesel oil a few years ago, won't necessarily look so good today!
But....one must also be careful, because street bikes now have catalytic converters as well. Watch out for downgrades in the additive package of "manufacturer branded" motorcycle oils as well!!! Check the bottle, is the oil still API SG or not???
Just for the record, there isn't an oil of any kind that has an additive package as robust as any Maxima
motorcyle oils do for example....seeing you mentioned that as a criteria. (And, just for the record, I don't run Maxima
so don't mistake this for a Maixma commercial....I run Redline which has a nice robust additive package as well!) http://www.sportride...l/photo_03.html
Appearently, the word "diesel" makes you feel good about an oil! As for me, the words "motorcycle specific", API SG/JASO MA
is what will continue to make me feel good about an oil for an engine with an integrated transmission.