FWIW, there's essentially two "camps" in motor oil these days: Japan/USA, and Euro.
"We" decided the "green" thing to do is to use the thinnest oil grade we can get away with, to reduce friction, and thus up MPG. We also use oils with "weak" (IMO) additive packs, to extend cat life. The downside of this is comparatively more frequent changes, and if you push the vehicle hard, you might have your oil thin excessively as it heats up.
Europe decided they would be "green" by pushing the oil change interval out as far as humanly possible, and not worry about the 0.5% MPG increase. To that end, they spec "thick" oils, that are on the "thick side" of their grade, and are generally all synthetic. They also tend to have stouter additive packs.
ILSAC and API are essentially complimentary grades. ACEA is the Euro version, and is often "mutually exclusive" W/R/T ILSAC: ACEA oils are typically too thick to earn the "Resource Conserving" label.
Just go ahead and use the latest API grade. Once you get out of warranty, you might want to think about stepping up a grade, esepecially in summer.