Oil temps and relation to HTHS?

[chris719]

Ok...I've been looking at (dash) observing, logging, and recording oil temps somewhat obsessively for my Sportwagen since buying new 6 years ago. I have noted a slight highway speed increase in them since switching to HPL a few years ago. My question for the fine folks of BITOG is....is this possibly related to higher HTHS with the HPL Euro 5W40 I use vs. other popular Euro 5W40s? Discuss.

I also believe it has to do with the VM/VIIs used which may show temporary shear in some areas that HTHS doesn’t seem to quantify. For example, Mobil and Porsche claim ESP X3 0W-40 with 3.8 HTHS has better fuel economy than ESP 5w30 and other C30 oils that are around 3.5 cP.