Bango Refining, USA, was using fixed-bed clay process for upgrading distillates recovered from used oil. The product had poor color, poor oxidation stability and there was no control over reduction of sulfur in the final products. From March 2009, with the Sequoia-supplied hydrotreater, Bango Oil started making Group 2+ base oil product that is ‘water white’. In 2012, the small hydrotreater was expanded to more than double its capacity. Sequoia carefully checked every equipment, every line and every instrument to make this expansion a success at minimum cost and little downtime.