quote:I wish it was true Bror, but I have called many companies (including Redline on their "SAE Racing Oils") and they all told me the same thing - they all use VI improvers. The only one that I have found is Amsoil SAE 30 - they have assured me that there are zero VI improvers in this formulation. They also did say that their 10W30 and 15W40 oils contain the least amount.
Originally posted by Bror Jace: As for the original question posed in this thread, I thought most REAL synthetic (Group IV & V base) oils of 10W30 weight had no viscosity index improvers. Conversely, I thought all 5W30 weights, even true synthetics, had some VII in them.