A feedstock containing at least 1 wt % butenes, at least 1 wt % pentenes, at least 1 wt % hexenes, at least 10 wppm C.sub.4 dienes, at least 10 wppm C.sub.5 dienes, and optionally at least 10 wppm C.sub.6 dienes can be selectively hydrogenated over a catalyst (e.g., a noble metal) to form a stream containing 100 wppm to 4000 wppm total dienes. The hydrogenated stream, and an olefinic recycle stream having less than 10 wt. % C.sub.1+ moieties, can be contacted with a molecular sieve catalyst, e.g., at a recycle to feed ratio between 0.1 and 3.0, at a WHSV of at least 1.0 based on olefin in the feed, and at a reactor .DELTA.T no greater than 40.degree. F. (22.degree. C.), thus forming a reaction product that can then be separated into a distillate, e.g., having from 1 wt % to 30 wt % non-normal C.sub.9 olefins, and the aforementioned olefinic recycle stream.