12. Which one is true: Conversion is needed to produce more fuel oil. Conversion always increases diesel yields only. Conversion is needed to adjust CDU yields to the market demand breakdown. Yields are distillation yields which are determine by crude oil quality only. 13. Which one is true: The main drivers of Refinery Margins are price differentials between feeds and products. The main drivers of Refinery Margins are capex costs The main drivers of Refinery Margins are fixed and capital cost. The main drivers of Refinery Margins are mass balances. 14. An existing refinery in order to respond to daily price differentials can change: Its configuration from Hydro-Skimming to FCC conversion. Crude mix, Cut Points, Units Severities, Capacity and refinance its loan. Crude oil purchase price. Crude mix, Cut Points, Units Severities, Capacity blending mixes