Gage

An instrument or device for measuring, indicating or comparing a physical characteristic.

Galling

A form of wear in which seizing or tearing of the gear or bearing surface occurs.

Generated contaminant

Caused by a deterioration of critical wetted surfaces and materials or by a breakdown of the fluid itself.

Graphite

A crystalline form of carbon having a laminar structure, which is used as a lubricant. It may be of natural or synthetic origin.

Gravimetric analysis

A method of analysis whereby the dry weight of contaminant per unit volume of fluid can be measured showing the degree of contamination in terms of milligrams of contaminant per liter of fluid.

Gravity

See Specific Gravity; API Gravity.

Grease

A lubricant composed of oil or oils thickened with soap, soaps or other thickener to a semisolid or solid consistency.