Hi 78F350,
Low SAPS. There are different ACEA standards for low SAPS oils. Some have a lowered HTHS. So i have to go more in detail:
A1/B1:
Standard quality, SAE 0W-30, 5W-20, 5W-30, 10W-30, normal oil intervals, lowered HTHS-viscosity (2,9 - 3,5 mPa*s)
not recommended
A3/B3:
Higher quality, shear stable, SAE 0W-X, 5W-X, 10W-40, 15W-40, 15W-50, 20W-50 for longer intervals, high wear protection, HTHS-viscosity (>3,5 mPa*s)
Recommend, but engine wasn't designed for the longer intervals (means engine sensors test the engine oil quality permanently). So can be used, but has to be changed in the intervals given by Porsche. Yearly or 15.000 Km.
A4/B4:
like A3 / B3 but also for DI-Diesel including Common Rail-Diesel, SAE 0W-30, 0W-40, 5W-30, 5W-40, 10W-40; A4 reserved for DI-Otto, high wear protection, longer intervals, HTHS-viscosity (>3,5 mPa*s)
Because it's a Diesel engine oil it had complete different detergents and much more. My point of view: not recommended.
A5/B5:
Performance like A3 / B4, SAE 0W-20, 0W-30, 5W-30, but lowered HTHS-viscosity like A1 / B1 (2,9 - 3,5 mPa*s), for longer intervals, lower fuel consumption.
Absolutely not recommended. Engine wasn't designed for that.
C1:
low SAPS oil with lowered HTHS-viscosity > 2,9 mPa*s, low viscosity (0W-X, 5W-X), Performance like A5/ B5, but with lowered sulfate ash, phosphor, sulfur.
Absolutely not recommended. Engine wasn't designed for that.
C2:
mid SAPS Öl with low HTHS-viscosity > 2,9 mPa*s, low viscosity (0W-X, 5W-X), Performance like A5/ B5 but with higher sulfate ash, phosphor, sulfur as C1-04.
Absolutely not recommended. Engine wasn't designed for that.
C3:
mid SAPS Öl with high HTHS-viscosity > 3,5 mPa*s, low viscosity (0W-X, 5W-X), Performance like A3/ B4 with with higher sulfate ash, phosphor, sulfur as C1-04.
Depends on sulfate ash, phosphor, sulfur. As said - no sulfur and sulfate ash would be best. I don't know about the US fuel. Sometimes fuel does also contain sulfur.
So i always go with a A3/A4 oil that also has a A40 Porsche approval.
A good HTHS is above 4.0. The oil i use at the moment has a HTHS mPa·s at 150ºC ASTM D 4683 of 4.3.
And hey, this is only my personal opinion and all marketers, believers and everybody else can do and like and use what they think it's right for their engine.
Regards, Markus