To convert the density of crude oil into its specific gravity, you can use the following formula:

Specific Gravity = Density of Crude Oil (at 60°F) / Density of Water (at 60°F)

The density of water at 60°F is approximately 62.4 pounds per cubic foot (lb/ft³), or 1 gram per cubic centimeter (g/cm³).

Therefore, if you have the density of crude oil in lb/ft³ or g/cm³, you can calculate its specific gravity by dividing the density of crude oil by 62.4 (if the units are lb/ft³) or 1 (if the units are g/cm³).

Here's an example:

If the density of crude oil is 55.5 lb/ft³:

Specific Gravity = 55.5 lb/ft³ / 62.4 lb/ft³ = 0.889

So, the specific gravity of the crude oil is 0.889.