...Bottom line:
For a given viscosity range, the less VI improvers in the oil, the better the oil.
Why? You're implying that those evil VI improvers in Mobil 1 are somehow detracting from its performance, as an oil, when compared to one of your boutique ester-based brands with, ostensibly, fewer VI improvers. Even
if this was true, most here have already agreed that "VI-improver-infested" Mobil 1 is way more oil than we will ever really put to any kind of ultimate test, so why are we picking fly specks out of pepper? I mean come on, what kind of punishment are you inflicting on your engine (on the street
or on the track) that our daily drivers, or the C6Rs that are running at Le Mans, are not seeing?
For the sake of quelling an argument, I will concede that it is possible that, way out on the far edges of the oil-performance/longevity envelope, there may be ester-based oils that will "out-perform" Mobil 1 in some way. Having said that though, I also have to say that, given engines in sound condition, I have never met (and will never meet) anyone who had (or will have) cause to
regret using Mobil 1...and that's without considering the cost/convenience factor. The cost/benefit consideration for ester-based oils is a lose/lose. I get my Mobil 1 at the local farm supply outlet for $6/quart. Whenever I look for Amsoil or Red Line...well, I have to
look for Amsoil or Red Line and, unless I'm willing to drive for more than an hour or buy it online and pay shipping on top of the almost-double price of the oil, it isn't even readily available to me.
My time and money are both finite resources, yet I would gladly spend them both to obtain and use ester-based oil if it would in some way benefit my car to switch away from Mobil 1...but since it won't, I don't. You may live near an Amsoil or Red Line distributor...if so, availability is no issue for you. That leaves the issue of cost...and if you're flush, that's no issue either and I'm happy for you. By all means, enjoy using Red Line or Amsoil. They're terrific oils, but so is Mobil 1...and you can find it almost anywhere, and at far less cost.