Fuels can vary by so many different properties. The biggies are octane, oxygen, lead content, and something called specific gravity, which measures the ratio of a substance’s density against a standard explains Zachary Santner, technical specialist with Sunoco Race Fuels. When that substance is a liquid, that standard is water. Gasoline weighs less than water, and most blends have a specific gravity somewhere between 0.7 and …
