Dimensionless ratio of the oil density \rho_O to the water density \rho_W, both taken at reference conditions (normally at STP, otherwise should be specified in the context):
| (1) | \gamma_o = \frac{\rho_O}{\rho_w} |
See also
Natural Science / Physics / Fluid density / Specific gravity
[ API gravity ][ Gas specific gravity (γg) ]