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Originally Posted by F87source
The thing is UOA's don't lie and it still shows these FE oils don't protect as well because they keep prioritizing fuel economy.
2 year oci's would be a stretch, but with ll01 certificatations it might be doable because ll01 has insanely stringent oxidation standards. But with Pao heavy oils it probably won't make it 2 years because paos and esters oxidize too quickly, and why Castrol edge 0w30 and 0w40 don't have BMW ll01 certificatations because it can't meet the stringent oxidation tests.
I wouldn't call the b58 a low stressed engine, it's running a bit more boost than the n55 and n54 stock, it revs to 7k which is still really high compared to other engines on the market, and the main issue is that it still runs very hot oil and coolant temps (for efficiency) like the n5x engines did. So I wouldn't want to run an FE oil let alone a 20 weight FE oil in the 2.6 - 3.1 HTHS area. If 0w30 fe oil was considered to be not too good (with UOA's on BITOG) with an HTHS over 3.0 the 20 weight version isn't going to improve upon that, it likely would be even worse.
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I'd look at a high stressed stock engine as something putting out over 100bhp per litre naturally aspirated, or 150bhp forced induction and revving over 7,500RPM. The only stock BMW engines I would put into that classification are ///M orientated ones at the moment. Needs high piston speeds and induction pressures to have to worry about using anything other than a mainstream oil (whcih 0w20 is right in the middle of these days).
Other than a few points of discussion on BITOG and some car forums, I don't see stock engines giving anything unusual using 0w20 oil. Many oil interpretations also can't separate oil chemistry from engine chemistry for many of the elements. I don't know of anyone who has bought a new car over the past 10 years that has any oil related issues. Googling UOA for b58 brings up lots of stock engines with Blackstone reports indicating great oil results with 0w20 fill. Non-stock engines are a different matter though, as they are operating outside of the manufacturer design parameters (higher bearing loads due to increased boost, higher redlines, richer mixtures, etc would all invalidate stock maintenance needs or warranty for that matter)..
Empirically of the tens of milions of cars put on the road around the workd over the past 15 years running Xw20 oil, there doesn't seem to be any statistical issue of longevity with vehicle mechanical reliability as good as it has ever been.
In the BMW group 2021 2.5 million vehicles produced, the majority now have 0w20 from the factory. The majority of Porsches also now leave the factory with C20 certified 0w20 (most are SUVs these days, of course). I can't think of a mainstream manufacturer worldwide that isn't specifying either 0w16 or 0w20 on most of their ICE vehicles these days.
If you see an impending implosion of engines due to oil failures before the rest of the vehicle is ready for the scrap heap, then maybe a wise move to invest in engine rebuilders?
