LL-01 is thats called an XODI oil, for extended oil drain interval. with mostly highway driving its rated for 30000K (more like 10000K for regular driving, we dont drive to work on the autobahn).
OK, so let me make sure I understand. For normal US traffic speeds, driving to work everyday, temps from 0-100F, and just the very rare occasional foray into triple digits speeds, this is the oil to use.

Is 20,000 mi a reasonable interval?

Given this, exactly what brand and weight should I look for?