The present disclosure provides base stocks and or diesel fuel, and processes for producing such base stocks and or diesel fuel by polymerizing alpha-olefins and internal olefins. The present disclosure further provides polyolefin products useful as base stocks and or diesel fuel. In at least one embodiment, a process includes: i) introducing, neat or in the presence of a solvent, a feed comprising a branched C5-C30 internal olefin, with a catalyst compound comprising a group 8, 9, 10, or 11 transition metal and at least one heteroatom and ii) obtaining a C6-C100 polyolefin product having one olefin, a methylene content of from about 1 wt % to about 98 wt %, and or a methyl content of from about 1 wt % to about 75 wt %. The feed may further include a linear C4-C30 internal olefin, a C2-C30 alpha-olefin, or a mixture thereof.