April 7, 2011– Frontier Oil Corporation (NYSE: FTO) plans to announce results for the quarter ended March 31, 2011 on Thursday, May 5, 2011. Management has scheduled a conference call for the morning of May 5 th at 10:00 a.m. CT to discuss the financial results and business outlook. To access the call, which is open to the public, please dial (800) 447-0521 (international callers (847) 413-3238), passcode 29497899. A recorded replay of the call may be heard through May 19, 2011 by dialing (888) 843-7419 (international callers (630) 652-3042), passcode 29497899. In addition, the real-time conference call and a recorded replay will be available via webcast by registering from the Investor Relations page of our website www.frontieroil.com. Frontier operates a 135,000 barrel-per-day refinery located in El Dorado, Kansas, and a 52,000 barrel-per-day refinery located in Cheyenne, Wyoming, and markets its refined products principally along the eastern slope of the Rocky Mountains and in other neighboring plains states.