Undefined Fuel-reserved For Proprietary Exclusive -

Until the day the proprietary veil lifts, the rest of the engineering world will watch, measure, and wonder what exactly is sloshing around in that sealed, silent reserve.

When a fleet or a fuel station offers a specialized blend (e.g., a specific racing fuel, a custom additive blend, or a local experimental biofuel) that isn't on the national list, they use these "Proprietary" codes to: undefined fuel-reserved for proprietary