Despite adding a level of protection (like antiwear) to an oil or a particular function (like detergency) it's important to note that additives generally compromise the base oil, not enhance it without compromise....i.e., more is not always better. For example, you can't just throw a bunch of zinc (an antiwear agent) into an oil and expect it to always protect better. Additives are not lubricants, per se. It's the job of an chemist to balance those trade-offs. Despite adding certain limited advantages, additives actually compromise the base oil.
Quick note -- For base oil we know there are different levels of quality. That's also true of the additives market; there are different levels of quality. With V.I. for example, Amsoil uses the best out of the 6 possible grades of Viscosity Improvers (or so i'm told) their top choice coming out of Europe.
My guesses: Pennzoil might win the cold flow test. Amsoil might win the evap (Noack) test. None of the test results should be significant. Not sure how Penrite got into the semifinal -- it totally bombed the evaporative test -- but those in the Northeast changing oil every 3,000 - 7,000 should to take a close look at Pennzoil for its cold flow capability. That was impressive.
And its price/performance ratio is exceptional too.
Considering Amsoil's extended service life it might well be the better bargain, but only if you change oil once-a-year (or 25,000 miles) as specified. Otherwise Amsoil seems like an overkill; paying for longevity you won't need or use.
As a DYI customer I mostly use Pennzoil Ultra now. But if traveling cross country 6,000 - 7,000 miles or putting the engine through its WOT paces over Atlanta's Blood Mountain (or both) Amsoil provides better peace of mind after I get past 5,000 miles, and especially 7,500.
People say freeway driving is easier on a car. I'm not so sure that still applies if you're doing 80mph all day when it's 105 degrees outside, with the A/C going full blast and car loaded to the gills. I tend to think that's a pretty brutal environment for an engine.
Can't wait for the next batch of UOA to get posted. Then, let's share our findings with Project Farm!