[edycol]

Several clarifications that might help folks here.
All LL specifications were updated in 2018 to include timing chain test. I personally would stick to LL oil.
Now, bit complicated part:
1. B generation engines take pretty much anything, from 0W20 to 5W40 or 0W40 (LL01 or LL04 oils). DIfference is in markets. In the US they use 0W20 LL17FE to meet CAFE requirements. As seen on some markets they use 0W30 LL01FE. Take into consideration that FE means what it is: fuel efficiency.
2. Vehicles equipped with GPF should NOT run anything LL01, FE or not. LL01 are so called High-SAPS oils. The sulfated ash and phosphorus content is too high for GPF and will shorten GPF life. If you want to run thicker oil, LL04 is way to go for those with GPF.
3. If you are leasing vehicle, stick to whatever BMW is putting in. No brainer there. If you bought vehicle and you plan on keeping it: LL01 (NOT FE one) for vehicles without GPF and LL04 for vehicles with GPF.

Difference between FE oils and regular ones:
FE oils have lower HTHS (High Temperature High Shear). HTHS is resistance of oil to temporary or permanent loss of viscosity. Higher number, more resistance. But, you do not want too high either. LL01 and LL04 have minimum requirement of 3.5cp HTHS. For example BMW TPT 5W30 has HTHS of 3.6, which is excellent for so called heavy W30 oil. Most 0W40 and 5W40 oils have HTHS between 3.6 and 3.9.
LL01FE oils have HTHS around 3, and that is in range of ILSAC GF5/6 5W30 oils like Mobil1 5W30 one can buy in Wal Mart. Imo, bit to low for B58.
0W20? I would not put that in my BMW if someone paid me. But, BMW gets EPA bump on mpg using those oils.

Castrol 0W40 not LL01?
Castrol did not decide to drop LL01. Approvals for oils are cheap (around $5k). Reason is that with 2018 update of oil approvals, BMW increased already extremely high oxidation requirements to even higher levels. 0W oils with HTHS above 3.5 have a bit higher oxidation as they utilize either more Esters (like M1 0W40 FS) or use more viscosity improvers (cheaper 0W40 oils). I personally would stick to approved LL01 or LL04 oils bcs. of that timing chain test that updated approvals have.
Hope this clarifies topic a bit. Any questions? Ask.