1 QUAKER STATE CORPORATION AND SUBSIDIARIES EXHIBIT 11 Computation of Net Income Per Share (in thousands except per share data, unaudited) Quarter Ended Six Months Ended 6/30/98 6/30/97 6/30/98 6/30/97 =================================================================================================================== 1. Net income $ 1,775 $ 8,844 $ 3,393 $ 15,709 =================================================================================================================== 2. Average number of shares of capital Stock outstanding--Basic 36,421 35,104 36,361 34,992 3. Shares issuable upon exercise of dilutive stock options outstanding during the period, Based on average market prices 815 226 546 164 4. Average number of capital and capital equivalent 37,236 35,330 36,907 35,156 shares outstanding--Diluted (2 + 3) 5. Net income per capital and capital equivalent Share - Basic (1 divided by 2) $ 0.05 $ 0.25 $ 0.09 $ 0.45 =================================================================================================================== 6. Net income per capital share assuming full Dilution - Diluted (1 divided by 4) $ 0.05 $ 0.25 $ 0.09 $ 0.45 =================================================================================================================== 17