NOVELTY - Dimerized product formed from oligomers comprises: (a) at least one oligomer-based composition or feedstock comprising terpene(s), alpha -olefin oligomer(s), or related olefins; and (b) at least one solid acid catalyst to feedstock for isomerization, where oligomer-based composition or feedstock and catalyst are converted into dimerized product (having less than 2 wt.% total oligomers) by e.g. (a1) isomerization utilizing heat of protonation, (b1) maximizing concentration of reacting olefin during protonation, and (c1) utilizing minimum reaction temperature zone to extend catalyst lifetime.    USE - The dimerized product is useful for producing the saturated hydrocarbon biofuel (claimed).    ADVANTAGE - The dimerized product: is highly pure; can be produced in a cost effective manner; and provides fuels with high flashpoints and superb cold flow properties.    DETAILED DESCRIPTION - Dimerized product formed from oligomers, comprises: (a) at least one oligomer-based composition or feedstock comprising terpene(s), alpha -olefin oligomer(s), or related olefins; and (b) at least one solid acid catalyst to the feedstock for isomerization, where the oligomer-based composition or feedstock and the catalyst are converted into a dimerized product having less than 2 wt.% total oligomers by processes of (a1) isomerization utilizing heat of protonation, (b1) maximizing the concentration of reacting olefin during protonation, (c1) utilizing a minimum reaction temperature zone to extend the catalyst lifetime, (d1) decreasing trimer and oligomer formations via an active recycle protocol to produce dimerized products in the absence of trimeric, tetrameric, and up to octameric, and (e1) utilizing a first fractionation process that mildly reduces pressure for the evaporation of unreacted feedstock to produce a dimerized product. An INDEPENDENT CLAIM is also included for a saturated hydrocarbon biofuel, comprising (a) and (b) as above per se, where the saturated hydrocarbon biofuel is produced by (a1)-(e1) as above per se, processing the produced dimerized product in a hydrogenation system/device to produce fully saturated hydrocarbon dimer products, introducing at least one catalyst into the hydrogenation process, processing the fully saturated hydrocarbon dimer products through a hydrocracking reactor system/device to reduce the molecular weight of the saturated hydrocarbon dimer products and/or to produce a lower boiling fuel product from the fully saturated hydrocarbon dimer products, introducing the catalyst into the hydrocracking process, introducing at least one reagent into the hydrogenation process and the hydrocracking process, and processing the lower boiling fuel product through a second fractionation process to produce a fully saturated hydrocarbon biofuel with sufficient flashpoint and cold flow properties from the lower boiling fuel product.