Refinery gasoline contains C-5 alkanes and alkenes that are being displaced due to regulations on maximum seasonal Reid vapor pressure (RVP) limits and increased blending of ethanol. As volumes of displaced C-5'S increase, technologies for returning C-5'S to the gasoline or diesel pools become increasingly important. Isolation of C-5 streams followed by dimerization/oligomerization of the C-5 olefins is one route to return displaced C-5'S to the gasoline pool. Large pore, acidic zeolite catalysts have been evaluated for this purpose. The process results in an overall volume loss due to volume contraction and a possible loss of research octane number (RON).