Thanks Jukka. I used the glossary to check what "API gravity" means since I was curious to know what "37 API oil" reported for Twiga-1 means. This is what I found:
A specific gravity scale developed by the American Petroleum Institute (API) for measuring the relative density of various petroleum liquids, expressed in degrees. API gravity is gradated in degrees on a hydrometer instrument and was designed so that most values would fall between 10° and 70° API gravity. The arbitrary formula used to obtain this effect is: API gravity = (141.5/SG at 60°F) - 131.5, where SG is the specific gravity of the fluid.
So: 37= (141.5/SG) - 131.5 implies SG = 0.84.
The Twiga-1 oil appears to me to be fairly liquid since it is 16% lighter than water.