<PAGE>   1

                                                                      Exhibit 11

                               CRYSTAL OIL COMPANY

           COMPUTATION OF INCOME (LOSS) PER COMMON SHARE (In Thousands
                       Except Share and Per Share Amounts)
                                   (Unaudited)


<TABLE>
<CAPTION>
                                                  Three Months Ended                          Six Months Ended
                                                         June 30                                   June 30
                                            ---------------------------------          --------------------------------
                                                1998                  1997                 1998                 1997
                                            -----------           -----------          -----------          -----------
<S>                                         <C>                   <C>                  <C>                  <C>        
Earnings (loss) per common share
  Net income (loss)                         $      (224)          $       495          $       371          $     1,309
                                            ===========           ===========          ===========          ===========

  Weighted average of common
    shares outstanding                        2,668,122             2,665,622            2,668,122            2,665,622
                                            ===========           ===========          ===========          ===========

Earnings (loss) per common share $                 (.08)          $       .19          $       .14          $       .49
                                            ===========           ===========          ===========          ===========


Earnings (loss) per common share -
  Assuming dilution
  Income (loss) from operations             $      (224)          $       495          $       371          $     1,309
  Adjustments to income (loss)
    (net of income tax)                              --                    --                   --                   --
                                            -----------           -----------          -----------          -----------
  Adjusted net income (loss)                $      (224)          $       495          $       371          $     1,309
                                            ===========           ===========          ===========          ===========

  Weighted average of common
    and common equivalent
    shares:
      Outstanding                             2,668,122             2,665,622            2,668,122            2,665,622
      Assuming conversion or
        exercise of:
          Stock options, net
            of treasury shares                   39,979                27,954               39,979               27,823
          Senior preferred
            stock                                33,274                33,274               33,274               33,274
                                            -----------           -----------          -----------          -----------
                                              2,741,375             2,726,850            2,741,375            2,726,719
                                            ===========           ===========          ===========          ===========

Earnings (loss) per common share -
  Assuming dilution                         $      (.08)          $       .18          $       .14          $       .48
                                            ===========           ===========          ===========          ===========

</TABLE>