Quote:
Originally Posted by F87source
The reason why I brought the m2 in is because the same uninformed sentiment of oil was shared as well.
I have a newer version of ista and the b58 and s58 is still checked in the oil comparability charts, there have been no changes to bearings or oil squirters during that time either so oil clearance shouldn't have changed and thus isn't an issue. The same was said about the m2 and when bearing tolerance data was pulled up it proved BMW specced enough tolerance, and all the speculation about tolerance was nonsense as proven by BMW's approval of low kv100 40 weight oils for ll01. What did change during 2016 (b58 release) and now is stricter German emissions which is why thinner oils are being used.
UOA's show increased wear with FE oils, that's where the doubt comes in. Then you look at ll01 approved oils which generally come with Porsche a40 (multiple hour Nurburgring test to ensure oil doesn't break down) and mb229.5 approvals, then you see how much more stringent these tests are and you see ll01 has a timing chain test which should be relevant for the b58 since the timing chain is in the rear of the engine making it impossible to service without dropping the motor. So you start to see better certifications as well when moving to a better oil.
BMW does have a mandated minimum HTHS ll01 is 3.5, but the reason why they're going thinner has nothing to do with what the engine can handle, it has to do with parasitic loss and emissions. So you want to have a good HTHS for the viscosity the engine can utilize which will result in as much protection as feasibly possible and this is why base stock is important because you can achieve major HTHS ratings without sacrificing viscosity. motul sport 300v 40 weight oil gets into the high 4 HTHS range due to its heavy ester base stock and that's almost 10w60 oil without the viscosity penalty. It's about finding the balance between shear strength and viscosity without going too thick, and FE oils have been proven to be garbage for protection and BMW moving to an even thinner fe oil doesn't help.
Btw GDI engines have more fuel dilution issues than pi engines, a thinner oil will suffer even more from that and thus sacrifice even more protection.
Look at some b58 UOA and you'll start to see BMW Fe oils suck vs. non Fe oils.
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If you have any proper peer reviewed info on why FE oils are not adequate, I would be interested to review it, as tribology research doesn't seem to correlate with Internet oil paranoia, neither do statistical failures from reliability info for vehicles running the B58 engine.
From the data on Motul Sport 300V 5w40, at an HTHS of 4.5 it is still quite a way from Castrol 10w60 with a HTHS of 5.2, but again HTHS in itself has no significant meaning when the engine is engineered to use a lower viscocity oil with a subsequently lower HTHS.
I've seen plenty of good UOAs from BMW 0w20 oils on stock engines, just can't compare with the results from a non-stock engine.