EXHIBIT 16 Office of the Chief Accountant Securities and Exchange Commission 450 Fifth Street, N.W. Washington, D.C. 20549 April 3, 2002 Dear Sir/Madam: We have read Item 4 included in the Form 8-K/A dated April 3, 2002, of Valero Energy Corporation to be filed with the Securities and Exchange Commission and are in agreement with the statements contained therein. Very truly yours, /s/ Arthur Andersen LLP - ----------------------- ARTHUR ANDERSEN LLP