The two oil trains that derailed and burst into flames in recent weeks in northern Ontario were both carrying synthetic crude to Valero Energy Corp's refinery near Quebec City, the U.S.-based company said. The CN Rail derailment came less than a month after another CN train carrying oil went off the tracks and ignited in northern Ontario. The railway had said both were carrying crude from Alberta, but declined to give their exact destination. "We take safety very seriously, so we're concerned anytime there's an incident," said Valero spokesman Bill Day. "Despite the number of rail incidents recently, it is very rare for cargo not to be delivered to its destination safely." Day said all of the rail companies Valero works with, including CN Rail, have good safety records. Synthetic crude is produced from Alberta's oil sands in upgrader plants, and usually commands a premium to conventional crudes because it is lighter and easier to refine into valuable byproducts such as gasoline. Valero's Jean Gaulin refinery is in Levis, across the St. Lawrence River from Quebec City. In May 2013, the company said it would build a rail off-loading facility at the Jean Gaulin refinery so it could start using Western Canadian crude rather than relying on pricier imports. The company told Reuters it would take light, sweet Western Canadian crude rather than heavier oil sands crude. Shipments of North American crude to the refinery ramped up early last year. On a July earnings call, the company said North American grades made up 83 percent of the refinery's feedstock in the second quarter of 2014, up from 45 percent in the first quarter and 8 percent higher than a year earlier. Separately, CN spokesman Jim Feeny said the train that derailed in February had been carrying petroleum distillates in addition to synthetic crude. "The contents of the tank cars are a subject of interest and the TSB will be testing the contents to determine what they were," said John Cottreau, spokesman for Canada's Transportation Safety Board, which is investigating the incidents. (Reuters)