Using hydraulic oil in gear applications

What would happen if hydraulic oil viscosity grade 68 was used instead of Mobilgear™ 600 XP 68 gear oil in gear applications?

Mobilgear 600 XP Series gear oils have outstanding extreme pressure characteristics and load-carrying properties. They are formulated to protect gear teeth from wear in its earliest stages, which can lead to significant gear tooth damage later on. Typical hydraulic oils do not have these properties, and are unable to provide sufficient wear protection for the higher leads on gear teeth.

Oils are typically formulated for use in specific applications. The proper balance of additives provides just the right protection for each application. So it’s important not to mix and match.

However, we do have oils that are “multi-application” oils like Mobil SHC™ 626, an ISO U668 circulating + gear oil. This oil provides protection in both gear and circulating systems.