These VOA’s are courtesy of JarHams on nasioc and are posted in the Car Part Reviews forum there.
The main reason for the voa’s is because Subaru of America sent a letter to dealers stating that the HPGO 75W-90 “is available as an alternative to the current K0322AA093 75W-90 Go Extra S Gear Oil that is supplied in a 5 Gallon Pail”, while inquiries to SoA by some customers (and even some dealers) claimed that it was the same product. Although the Extra S is made by Showa Shell Sekiyu and the HPGO is made by Idemitsu. Dealers have access to the MSDS, so maybe it will eventually show up soon on-line.
Both samples dated 1 Nov 2014 Extra S
(Similar to what we’ve already seen)
cSt Viscosity @ 100C 13.34
Comments: This is the sample of Extra S sample of 75W/90. The additives present are boron, calcium, magnesium, and phosphorus. The viscosity is correct for 75W/90 and there’s no moisture or insoluble present. The TAN is 4.8. This is serviceable oil. Subaru High Performance Gear Oil
(hey, who took my metallic additives?)
Viscosity @ 100C 15.04
Comments: This is the sample of the High Performance 75W/90. The additives are very different from the Extra S, so this is not the same oil. That’s not to say that one is better than the other or that this oil isn’t serviceable, but the two aren’t the same. No moisture or insolubles are present. The TAN is 3.4.
Is there any chance that sulfur in the HPGO is higher than in the Extra S?