Bruce is right. They did not include aromatics which are great film formers. Of course they have huge downsides too, most importantly oxidative stability. Aromatics and napthenics are good in certain areas that the more processed oil are not, and vice versa.
I wish they had tested more than one type of ester as well.
Yep, Tempest, the Group 3 and 4 basestocks have significantly better thermal conductivity than the lower group basestocks. Terry has brought that up a lot recently. As you can see from some of the other charts, Group 4 (and 3 to a slightly lesser extent) oils have weaknesses in some other areas, most disturbingly in film forming ability. They discuss shock absorption and I think (correct me if wrong) it indicates the higher group number basestocks don't do as well in that area. Noisy engine, anyone?
The effect of shear rate on viscosity cracked me up. A Newtonian fluid has same viscosity as all shear rates-shown as flat line. Look at the 20W-50 vs the straight 30 wt viscosity. At some shear rate, the 20W-50 viscosity takes a huge dump and eventually goes below the 30 wt! Same type thing as discussed in my other recent thread. The polymers also decrease film strength when high pressures are applied. SO high shear rate and high pressure combined really puts an oil with lots of polymers at a disadvantage in film strength. I wish I could get away from M1 0W-40 because of that but it's just too good at other things that I have not found a suitable replacement yet.
All this once again shows that great oil must be tailored to the application, with compromises always being made. No ingredients are just right in all ways.
Dad2leia, a chef is a food engineer, isn't he? Sort of?
