SEOUL/SINGAPORE, Dec 18 (Reuters) -
* South Korean refiner GS Caltex Corp has bought a rare cargo of Cold Lake crude, the company's first purchase in more than two decades of this Canadian oil grade, a company spokesman said on Monday
* The second largest refiner in South Korea bought 300,000 barrels of the heavy sour crude for delivery in the second half of February, he said
* GS Caltex is a joint venture between GS Holdings 078930.KS and Chevron Corp (NYSE:CVX) CVX.N