Now that would be a shear stable oil, it comes in two grades 10W30 and 15W40 according to this Mobil web pagehttps://www.mobil.com/en-US/Commercial-Vehicle-Lube/pds/GL-XX-Mobil-Delvac-Extreme
Both are API CK-4, ACEA E7 & E9, plus many OEMs, both have a strong TBN of 10.3
10W30 HTHS = 3.6 cP, KV100 = 11.8 cSt,
15W40 HTHS = 4.1 cP, KV 100 = 14.3 cSt,
They don’t mention ZDDP levels, but the 15W40 is API SL/SM rated, while the 10W30 is not. Given that Phos levels (from ZDDP) are more restricted for 30 grades than 40 grades, I read this as these being higher ZDDP oils. ZDDP is an anti-wear agent that protects the metal, but also an antioxidant that protects the oil itself. A VOA would be interesting.
The CCS limit for both those winter grades (10W and 15W) is 7000 cP (at -25 C and -20 C respectively), and they test out to be 6600 and 6100 respectively. This is getting close to the upper limits, which suggest to me that thicker base oil was used for the viscosity, and less polymer VII. So I would expect high shear stability and low Noack volatility.
All this on a synthetic base, says a very strong oil with a long life. Which is what Mobil is selling
Mobil Delvac Extreme is formulated with synthetic basestocks and a boosted additive system tailored to deliver extended performance for up to two times beyond OEM recommended oil drain intervals. The proprietary formulation delivers excellent wear protection, exceptional oxidation stability, and outstanding TBN retention. Mobil Delvac Extreme FE also provides outstanding resistance to oil consumption, oxidation, corrosive and abrasive wear, and high temperature deposits.