The Lexus was on dealer-provided 20W-50 dino oil. Not clear if the OCI was 10,000 km or less. Could you clarify that Falcon_LS?
For the BMWs, yes, they spec BMW LL-01 synthetic oil. They are either thick xW-30 or thin xW-40, with viscosity ranging from 11.5 to 14.0 cSt @100°C. The most popular ones are GC and Mobil 1 0W-40.
Again, the problem is the long OCI. For a hot and humid country like ours where traffic is severe and highway mileage is but a short percentage, the 15,000 mile/24,000 km OCI is way too long. I've seen too many oil-related problems for those that go beyond 10,000 km, especially for the 4-cyl ones that only have a 4.25 liter sump.
So I've decided that an ACEA A3/B4 dino or semi-syn within the correct viscosity range and changed every 5,000 km is the better way to go -- at least for our local conditions.