Based on these studies, and for these particular base stocks, it was determined that
propylene-derived polymer gasoline had blending octanes of 94 RON and 83 MON; these values are almost identical to the clear values measured on the blend stock so that there is no synergism between the propylene condensation product and the base stock. The situation with the propylene–butenes polymer gasoline is quite different. Here, the blend stock had RON and MON of 96 and 83, respectively, but it blended with the base stock at the 10% level as though the octane numbers of the blend stock were 103 RON and 95 MON, a clear display of synergism with the base stock. Slightly different but still very high blending values are obtained when blended at the 20 vol%
level. Naturally, the blending values decline progressively when the blend stock is added in higher and higher proportions, until they reach the clear measured values on the blend stock at a 100% blend stock proportion.