In the present study of experimentation, locally available biofuels, such as rubber seed oil (non edible oil), coconut oil, and palm oil (edible oils), were used as alternative fuels to diesel in a compression ignition engine. The properties of these oils, such as viscosity, specific gravity, calorific value, flash point, and fire point, were determined. The effect of temperature on viscosity of vegetable oils (rubber seed oil, coconut oil, and palm oil) was examined. It was found that the viscosity of coconut oil reduces drastically compared to rubber seed oil and palm oil at all temperatures (40-80 degrees C). High viscosity of vegetable oils was reduced by preheating to use directly in engines. The performance and emission characteristics of a single cylinder, direct-injection diesel engine were determined using diesel and vegetable oils (unheated and preheated conditions). The CO emission was reduced and performance improved for preheated vegetable oils. It is concluded that from the findings of experimentation, the preheated vegetable oils could be used as substitutes to diesel fuel for short-term engine operation.