The oil refining giant's board approved the spinoff of its CST Brands retail motor fuels and convenience store business, effective May 1. Valero Energy (VLO) will distribute 80% of the shares of CST Brands it holds, and CST will then begin trading on the NYSE under the ticker symbol "CST." Valero said it plans to hold onto the other 20% for at least 6 months. The refiner said it's received a letter from the IRS saying the spinoff will not be a taxable transaction for Valero. Shares rose 1.3% to 41.98.