Allegro
                Biodiesel Corporation

              6033
                West Century Blvd., Suite 1090

              Los
                Angeles, California 90045

              Tel:
                (310) 670-2093

              Fax:
                (310) 670-4107

              www.allegrobiodiesel.com 

            


    

     

    
      
        

      

    

     

    

       

      June
        13,
        2008

       

      Via
        Federal Express

       

      Attention:
        Ronda Carson

      JPMorgan
        Chase Bank, N.A.

      Escrow
        Services

      333
        South
        Grand Avenue, 36th
        Floor

      Los
        Angeles, CA 90065

       

      
        	 	
                Re:

              	
                Joint
                  Escrow Instructions re Escrow
                  Agreement (“Escrow Agreement”) by and among Diametrics Medical, Inc., the
                  Members and JPMorgan Chase Bank, N.A. dated as of September 20,
                  2006 

              


      

       

      Ladies
        and Gentlemen:

       

      Capitalized
        terms used herein without definition have the meaning ascribed thereto under
        the
        Escrow Agreement. Allegro Biodiesel Corporation (fka Diametrics Medical,
        Inc.,
“Allegro”) has submitted to you various demands for release from the Escrow
        Deposit under the Escrow Agreement. With the exception of the claim referenced
        in the May 16, 2008 joint escrow instructions of Allegro and the Member
        Representative, and as provided in the other June 13, 2008 joint escrow
        instructions, these claims have not yet been resolved by Allegro and the
        Member
        Representative.

       

      Allegro
        and the Member Representative have entered into an Agreement to Settle Certain
        Claims dated as of the date hereof (the “Agreement”) in order to set forth
        procedures pursuant to which Allegro and the Member Representative will resolve
        the remaining outstanding claims by Allegro. A copy of the Agreement is enclosed
        herewith. The Agreement provides that the parties will first attempt to
        negotiate to reach an amicable resolution of all outstanding claims by Allegro.
        If Allegro and the Member Representative are not able to resolve all such
        claims
        pursuant to such negotiations, the Agreement provides that Allegro and the
        Member Representative will submit such claims to binding arbitration in
        accordance with the procedures set forth in the Agreement. Either Allegro
        or the
        Member Representative may advise you in writing as to the identity of the
        arbitrator for such arbitration. At the conclusion of such binding arbitration
        the arbitrator will resolve all claims submitted to the arbitration, and
        will
        determine the amount of the Escrow Amount and the number of Escrow Shares
        to be
        released to Allegro, on the one hand, and the Members, on the other hand
        (the
“Award”). The Award shall be delivered to you by the arbitrator in writing.
        Allegro and the Member Representative hereby direct you to release the Escrow
        Amount and the Escrow Shares in accordance with the Award, without any further
        action or instructions of Allegro or the Member Representative.

       

      Please
        call Stephen Blevit of Sidley Austin LLP at 213-896-6029 with any questions
        regarding these joint escrow instructions.

       

      Very
        truly yours,

       

      
        	
                ALLEGRO
                  BIODIESEL CORPORATION

                 

                By:   
/s/
                  W. Bruce Comer,
                  III                             
                    

                Name:
                  W. Bruce Comer, III

                Title:  
                  Chief Executive Officer

              	
                 

                 

                /s/ 
                  Darrell
                  Dubroc                    

                DARRELL
                  DUBROC,
                  

                as
                  Member Representative