Saw this article and reminded me of something Molakule wrote about effectiveness of PAG base stocks in gl5 gear oils. I think Ford Motor Company sponsored this study.
https://www.energy.gov/sites/prod/files/2017/06/f34/ft023_gangopadhyay_2017_o.pdf
https://www.energy.gov/sites/prod/files/2017/06/f34/ft023_gangopadhyay_2017_o.pdf