Current book evaluates the effects of oxygenated alcohol/gasoline/diesel fuel blends on performance, combustion and emission characteristics in conventional reciprocating engines. On the one hand, in alcohol-gasoline blends, dual alcohols gasoline blends have not yet been sufficiently proven as suitable alternatives to single alcohol-gasoline blends in engines as far as performance is concerned. On the other hand, n-butanol-diesel, although it has a better miscibility factor in diesel than methanol or ethanol, is limited with regards to extensive application in the diesel engines due to its low cetane number. Engine performance was compared using single alcohol-gasoline and dual alcohol-gasoline blends, where the dual blends where constrained to meet the vapour issues regarding fuels and regulations. The blends were selected in terms of a combination by volume of one being higher alcohol (n-butanol) and the other, lower alcohol (methanol). The engines used for this study included a single-cylinder and a four-cylinder, naturally-aspirated, four-stroke spark ignition engines; a four-cylinders, four-stroke compression ignition turbocharged diesel engine.