A hydrocarbon composition comprises at least 90 wt. % of C.sub.9 to C.sub.20 non-normal olefins, non-normal saturates or combinations thereof based on the weight of the hydrocarbon composition, at least 2 wt. % and not greater than 25 wt. % of C.sub.9 hydrocarbons based on the weight of the hydrocarbon composition, and less than 15 wt. % of C.sub.17+ hydrocarbons based on the weight of the hydrocarbon composition, wherein said hydrocarbon composition has a specific gravity at 15.degree. C. of at least 0.730 and less than 0.775. The composition is produced by oligomerization of at least one C.sub.3 to C.sub.8 olefin and an olefinic recycle stream containing no more than 10 wt. % of C.sub.10+ non-normal olefins. The composition is useful in producing fuel blends, such as jet fuel and diesel fuel.