Everyone should watch the video where they fashioned both a transparent valve cover and pan on an old car. Changed the oil on it to have fresh oil. Then started it at -23 C (-9 F). After SEVERAL minutes there was still no oil flow to the overhead valves. Here's the Youtube video:
. You run the time indicator over with your mouse to about 1/2 way because most of the first half is their description of how they did the valve cover and pan.
Our research people once did a test at -40 C/F with a transparent valve cover on a Dodge or Plymouth 024 type engine with various oils and filmed the valve cover. EVERY oil they tested smoked the valve cover except Mobil 1.
A few years later, we merged with Mobil. Problem solved.
The only true synthetics for vehicle usage is by Mobil or Pennzoil. Mobil makes theirs out of poly alpha olefin, which is a plastics feedstock and therefore makes it expensive. Pennzoil make theirs out of natural gas, a cheap feedstock. Think all the Group V ones are stuff like esters that Exxon have made for years for jet/turbine engines. Amsoil's feedstock is Group IIi, not synthetic. It's all hydrotreated crude oil.