The term 'alternative to oil' can be summarized by two crossword solutions: GAS (3 letters) and OLEO (4 letters). GAS is a type of fuel derived from natural GAS, petroleum, or other hydrocarbon sources. It is used in many applications, including transportation, heating, and electricity generation. Oleo is a type of vegetable oil that is made from plant-based sources such as soybeans, sunflower, and canola. It is used in many food products, as well as in some industrial applications. Both GAS and oleo are viable alternatives to oil, and both have their own unique benefits and drawbacks.