That's why a lube schedule specs by product, not by viscosity. Typically, when I hear ISO 68 I'm thinking DTE 26 or Tellus 68 hydraulic oil. That is, no EP additives. When EP is called for, it is called for by name, as in XP68. Both make great gear oils, but one will eat up yellow metal bushings and one won't. If you want to get really confused, try to figure out which oil from Hangsterfer's has EP in it... they tend to refer to yellow metal eating tendencies by temperature instead of by additive, and they won't tell you which is which unless you call their customer support with an order for a thousand gallon tote. You can't regulate an oil company or require to disclose their "proprietary" products in this society. Which is why you always consult the lube schedule!