<PAGE>
                               GUARANTY AGREEMENT

      THIS GUARANTY AGREEMENT, dated as of September 27, 2002 (the "GUARANTY
AGREEMENT"), is made by TE PRODUCTS PIPELINE COMPANY, LIMITED PARTNERSHIP, a
Delaware limited partnership ("TEPPCO"), and MARATHON ASHLAND PETROLEUM LLC, a
Delaware limited liability company ("MAP" and together with TEPPCO, the "SPECIAL
GUARANTORS"), in favor of the holders from time to time of the Notes issued
under the below-described Note Agreements.

      WHEREAS, Centennial Pipeline LLC, a Delaware limited liability company
(the "COMPANY") and The Prudential Insurance Company of America ("PRUDENTIAL")
have entered into (i) a Revolving Note Agreement dated as of May 4, 2001 (as the
same may be amended, restated, supplemented or otherwise modified from time to
time, the "REVOLVING NOTE AGREEMENT"), pursuant to which the Company sold and
Prudential purchased (in each case subject to the terms and conditions set forth
therein) $10,000,000 aggregate principal amount outstanding from time to time of
the Company's senior floating rate revolving notes (together with any notes
issued in substitution or exchange therefor pursuant to the terms of the
Revolving Note Agreement, the "REVOLVING NOTES"), and (ii) a Master Shelf
Agreement dated as of May 4, 2001 (as the same may be amended, restated,
supplemented or otherwise modified from time to time, the "SHELF AGREEMENT" and
together with the Revolving Note Agreement, the "NOTE AGREEMENTS"), pursuant to
which the Company has sold and may from time to time hereafter sell and
Prudential and/or one or more Prudential Affiliates or Identified Purchasers
(each as defined in the Shelf Agreement) has purchased and may from time to time
hereafter purchase (in each case subject to the terms and conditions set forth
therein) senior fixed rate term notes of the Company in an aggregate principal
amount not to exceed $140,000,000 (together with any notes issued in
substitution or exchange therefor pursuant to the terms of the Shelf Agreement,
the "TERM NOTES" and together with the Revolving Notes, the "NOTES");

      WHEREAS, pursuant to the conditions of the Note Agreements, Panhandle
Eastern Pipe Line Company, a Delaware corporation ("PEPL"), TEPPCO and MAP
entered into, as guarantors thereunder, the Guaranty Agreement dated as of May
4, 2001 (as the same may be amended, restated, supplemented or otherwise
modified from time to time, the "ORIGINAL GUARANTY"), in favor of the holders
from time to time of the Notes issued under the Note Agreements;

      WHEREAS, (i) a Sponsor Default Event (as defined in the Original Guaranty)
has occurred with respect to PEPL, (ii) the Required Holder(s) (as defined in
the Note Agreements) have requested PEPL to provide Acceptable Credit Support
(as defined in the Original Guaranty) as provided by the terms of the Original
Guaranty, (iii) PEPL has not provided any part of such required Acceptable
Credit Support, and (iv) the Special Guarantors have elected, pursuant to, and
for the purposes provided in, Section 12(c)(ii)(B) of the Original Guaranty and
subject to the terms of this Guaranty
<PAGE>

Agreement, to provide Acceptable Credit Support by executing and delivering this
Guaranty Agreement;

      NOW THEREFORE, in consideration of, and in reliance on, the premises and
the terms and agreements herein contained, and for other good and valuable
consideration and reasonably equivalent value, each of the Special Guarantors
hereby covenants and agrees with, and represents and warrants to each holder of
Notes as follows:

1.    DEFINED TERMS. All capitalized terms used herein, unless specifically
      otherwise defined, shall have the meanings ascribed to them in, or by, the
      Original Guaranty. In addition, the terms defined in the introductory
      paragraph and recitals of this Guaranty Agreement shall have the
      respective meanings specified therein, and the following terms shall have
      the meanings specified with respect thereto below:

                  "SPECIAL PEPL EVENT DATE" shall mean the initial date that
            occurs on or after the effective date of this Guaranty Agreement on
            which PEPL (which term "PEPL", for the avoidance of doubt, includes
            any successor to PEPL or any assignee or transferee of PEPL's
            interest in the Company) possesses both a senior unsecured long-term
            debt rating of BBB- or better from S&P and a senior unsecured
            long-term debt rating of Baa3 or better from Moody's.

                  "SPECIAL PRO RATA PORTION" shall mean, as to each Special
            Guarantor and with respect to any of the Special Guaranteed
            Obligations, fifty percent (50%) of PEPL's Pro Rata Portion of the
            Guaranteed Obligations under the Original Guaranty.

2.    THE GUARANTY. Each of the Special Guarantors hereby irrevocably,
      unconditionally and severally (but not jointly) guarantees to each holder
      from time to time of any of the Notes, such Special Guarantor's respective
      Special Pro Rata Portion of (i) the due and punctual payment in full of
      the principal of, Yield-Maintenance Amount or Breakage Cost Obligations,
      if any, interest and all other amounts due under the Notes from time to
      time outstanding, when and as the same shall become due and payable,
      whether at stated maturity or by required or optional prepayment or
      purchase, by acceleration or otherwise (including interest due on overdue
      payments of principal, Yield-Maintenance Amount or Breakage Cost
      Obligations, if any, or interest at the rate set forth in the Notes or any
      other amounts due thereunder) which may become due under the terms and
      provisions of the Notes or the Note Agreements, and (ii) the full and
      prompt payment of all other obligations and liabilities of the Company
      under the Note Agreements or under any other Shelf Documents or Revolving
      Note Documents (collectively, the "NOTE DOCUMENTS") (all such obligations,
      covenants, conditions and agreements described in the foregoing clauses
      (i) and (ii) being hereinafter collectively referred to as the "SPECIAL
      GUARANTEED OBLIGATIONS"); provided, however, that the amount of Special
      Guaranteed Obligations owed at any time shall be reduced,


                                       2
<PAGE>

      pro tanto, by the aggregate amount indefeasibly paid in cash by, or on
      behalf of, PEPL in respect of its Pro Rata Portion of the Guaranteed
      Obligations. The guaranty in the preceding sentence is an absolute,
      present and continuing guaranty of payment and not of collectibility and
      is in no way conditional or contingent upon any attempt to collect from
      the Company, PEPL or any other guarantor of the Notes or upon any other
      action, occurrence or circumstance whatsoever; provided, however, in no
      event shall amounts paid by the Special Guarantors in respect of the
      Special Guaranteed Obligations be paid in duplication of amounts otherwise
      indefeasibly paid in cash by or on behalf of PEPL in respect of the
      Guaranteed Obligations, and if any such duplicative payment is made by a
      Special Guarantor, then upon written notice thereof to the holders of
      Notes from such Special Guarantor, which notice sets forth the amount of
      such overpayment, the holders of Notes shall as soon as reasonably
      practicable thereafter refund the amount thereof as directed in such
      written notice. In the event that the Company shall fail so to pay any of
      such Special Guaranteed Obligations, each of the Special Guarantors
      severally (but not jointly) agrees to pay its respective Special Pro Rata
      Portion of the same when due to the holders of the Notes entitled thereto,
      without demand, presentment, protest or notice of any kind, in lawful
      money of the United States of America, at the place for payment specified
      in the Notes and the Note Agreements. Each default in payment of principal
      of, Yield-Maintenance Amount or Breakage Cost Obligations, if any, or
      interest or any other amounts due on any Note shall give rise to a
      separate cause of action hereunder and separate suits may be brought
      hereunder as each cause of action arises. Each of the Special Guarantors
      hereby agrees that the Notes issued in connection with the Note Agreements
      may make reference to this guaranty.

      Each of the Special Guarantors hereby agrees to pay and to indemnify and
      save the holders of the Notes harmless from and against any damage, loss,
      cost or expense (including attorneys' fees) which such holder may incur or
      be subject to as a consequence, direct or indirect, of (i) any breach by
      such Special Guarantor or by the Company of any warranty, covenant, term
      or condition in, or the occurrence of any default under, this Guaranty
      Agreement, the Notes, the Note Agreements or any other Note Document,
      together with all expenses resulting from the compromise or defense of any
      claims or liabilities arising as a result of any such breach or default,
      and (ii) any legal action commenced to challenge the validity of this
      Guaranty Agreement, the Notes, the Note Agreements or any other Note
      Document.

3.    OBLIGATIONS ABSOLUTE. The obligations of each of the Special Guarantors
      hereunder shall be primary, absolute, irrevocable and unconditional,
      irrespective of the validity, regularity or enforceability of the Notes,
      the Note Agreements or any other Note Documents, shall not be subject to
      any counterclaim, setoff, deduction or defense (other than indefeasible
      payment and if indefeasibly paid, payments made by, or on behalf of, PEPL
      in respect of its Pro Rata Portion of the Guaranteed Obligations) based
      upon any claim such Special Guarantor may have against the Company or any
      holder of the Notes or


                                       3
<PAGE>

      otherwise, and shall remain in full force and effect without regard to,
      and shall not be released, discharged or in any way affected by, any
      circumstance or condition whatsoever (whether or not such Special
      Guarantor shall have any knowledge or notice thereof), including, without
      limitation: (a) any amendment, modification of or supplement to the Note
      Agreements, the Notes or any other instrument referred to therein (except
      that the obligations of such Special Guarantor hereunder shall apply to
      the Note Agreements, the Notes or such other instruments as so amended,
      modified or supplemented) or any assignment or transfer of any thereof or
      of any interest therein, or any furnishing, acceptance or release of any
      security for the Notes, (b) any waiver, consent, extension, indulgence or
      other action or inaction under or in respect of the Notes or in respect of
      the Note Agreements or any other Note Document; (c) any bankruptcy,
      insolvency, readjustment, composition, liquidation or similar proceeding
      with respect to the Company or its property; (d) any merger, amalgamation
      or consolidation of such Special Guarantor or of the Company into or with
      any other corporation or any sale, lease or transfer of any or all of the
      assets of such Special Guarantor or of the Company to any person; (e) any
      failure on the part of the Company for any reason to comply with or
      perform any of the terms of any other agreement with such Special
      Guarantor; or (f) any other circumstance which might otherwise constitute
      a legal or equitable discharge or defense of a guarantor. Each of the
      Special Guarantors covenants that, unless released in accordance with
      Section 13 hereof, its obligations hereunder will not be discharged except
      by payment in full of all of the Special Guaranteed Obligations.

4.    WAIVER. Each of the Special Guarantors unconditionally waives to the
      fullest extent permitted by law, (a) notice of acceptance hereof, of any
      action taken or omitted in reliance hereon and of any defaults by the
      Company in the payment of any amounts due under the Notes, the Note
      Agreements or any other Note Document, and of any of the matters referred
      to in Section 3 hereof, (b) all notices which may be required by statute,
      rule of law or otherwise to preserve any of the rights of each holder from
      time to time of the Notes against such Special Guarantor, including,
      without limitation, presentment to or demand for payment from the Company
      or such Special Guarantor with respect to any Note, notice to the Company
      or to such Special Guarantor of default or protest for nonpayment or
      dishonor and the filing of claims with a court in the event of the
      bankruptcy of the Company, (c) any right to the enforcement, assertion or
      exercise by any holder of the Notes of any right, power or remedy
      conferred in this Guaranty Agreement, the Note Agreements, the Notes or
      any other Note Document, (d) any requirement or diligence on the part of
      any holder of the Notes and (e) any other act or omission or thing or
      delay to do any other act or thing which might in any manner or to any
      extent vary the risk of such Special Guarantor or which might otherwise
      operate as a discharge of such Special Guarantor.

5.    OBLIGATIONS UNIMPAIRED. Each of the Special Guarantors authorizes the
      holders of the Notes, without notice or demand to such Special Guarantor
      and without affecting its obligations hereunder, from time to time (a) to
      renew,


                                       4
<PAGE>

      compromise, extend, accelerate or otherwise change the time for payment
      of, or otherwise change the terms of, all or any part of the Notes, the
      Note Agreements or any other instrument referred to therein, (b) to take
      and hold security for the payment of the Notes, for the performance of
      this Guaranty Agreement or otherwise for the indebtedness guaranteed
      hereby and to exchange, enforce, waive and release any such security, (c)
      to apply any such security and to direct the order or manner of sale
      thereof as the holders of the Notes in their sole discretion may
      determine, (d) to obtain additional or substitute endorsers or guarantors,
      (e) to exercise or refrain from exercising any rights against the Company
      and others, and (f) to apply any sums, by whomsoever paid or however
      realized, to the payment of the principal of, Yield-Maintenance Amount or
      Breakage Cost Obligations, if any, or interest or any other amounts due on
      the Notes and any other Special Guaranteed Obligation hereunder. Each of
      the Special Guarantors waives any right to require the holders of the
      Notes to proceed against any additional or substitute endorsers or
      guarantors or to pursue or exhaust any security provided by the Company,
      such Special Guarantor or any other person or to pursue any other remedy
      available to such holders.

6.    SUBROGATION. Each of the Special Guarantors agrees that it will not
      exercise any rights which it may have acquired by way of subrogation under
      this Guaranty Agreement, by any payment made hereunder or otherwise, or
      accept any payment on account of such subrogation rights, or any rights of
      reimbursement or indemnity or any rights or recourse to any security for
      the Notes or this Guaranty Agreement unless and until all of the
      obligations, undertakings or conditions to be performed or observed by the
      Company pursuant to the Notes, the Note Agreements and any other Note
      Document at the time of such Special Guarantor's exercise of any such
      right shall have been performed, observed or paid in full.

7.    REINSTATEMENT OF GUARANTY. This Guaranty Agreement shall continue to be
      effective, or be reinstated, as the case may be, if and to the extent at
      any time, prior to the Guaranty Termination Date, payment, in whole or in
      part, of any of the sums due to any holder of the Notes for principal of,
      Yield-Maintenance Amount or Breakage Cost Obligations, if any, or interest
      on the Notes or any of the other Special Guaranteed Obligations is
      rescinded or must otherwise be restored or returned by such holder upon
      the insolvency, bankruptcy, dissolution, liquidation or reorganization of
      the Company, or upon or as a result of the appointment of a custodian,
      receiver, trustee or other officer with similar powers with respect to the
      Company or any substantial part of its property, or otherwise, all as
      though such payments had not been made; provided, however, if subsequent
      to such rescission, restoration or return but prior to the date a Special
      Guarantor is obligated to make a payment hereunder as a result of any such
      rescission, restoration or return this Guaranty Agreement terminates as a
      result of the occurrence of the Special PEPL Event Date, then from and
      after that date, this Guaranty Agreement shall no longer be deemed to
      continue be effective or reinstated, as the case may be, and for the
      avoidance of doubt, any such post-rescission, restoration or return
      payment obligation of a Special Guarantor shall


                                       5
<PAGE>

      be cancelled. If an event permitting the acceleration of the maturity of
      the principal amount of the Notes shall at any time have occurred and be
      continuing and such acceleration shall at such time be prevented or the
      right of any holder of a Note to receive any payment under any Note shall
      at such time be delayed or otherwise affected by reason of the pendency
      against the Company of a case or proceeding under a bankruptcy or
      insolvency law, each of the Special Guarantors agrees that, for purposes
      of this Guaranty Agreement and its obligations hereunder, the maturity of
      such principal amount shall be deemed to have been accelerated with the
      same effect as if the holders of the Notes had accelerated the same in
      accordance with the terms of the Note Agreements, and such Special
      Guarantor shall forthwith pay such accelerated principal amount, accrued
      interest and Yield-Maintenance Amount or Breakage Cost Obligations, if
      any, or any other amounts due thereon and any other amounts guaranteed
      hereunder.

8.    PAYMENTS. Each of the Special Guarantors hereby severally (but not
      jointly) guarantees that its respective Special Pro Rata Portion of the
      Special Guaranteed Obligations will be paid to each holder of the Notes in
      lawful currency of the United States of America and in immediately
      available funds, at the times and places provided in, and otherwise
      strictly in accordance with the terms and provisions of, the Note
      Agreements and the Notes (regardless of any law, regulation or decree now
      or hereafter in effect which might in any manner affect the Special
      Guaranteed Obligations, or the rights of any such holder with respect
      thereto as against the Company or cause or permit to be invoked any
      alteration in the time, amount or manner of payment by the Company of any
      or all of the Special Guaranteed Obligations), without set-off or
      counterclaim and free and clear of, and without reduction for or on
      account of, any present or future income, stamp or other taxes, levies,
      imposts, duties, charges, fees, deductions, withholdings now or hereafter
      imposed, levied, collected withheld or assessed by any country (or by any
      political subdivision or taxing authority thereof or therein) excluding
      income and franchise taxes of the United States of America or any
      political subdivision, state or taxing authority thereof or therein
      (including Puerto Rico) (such non-excluded taxes being called "FOREIGN
      TAXES"). If any Foreign Taxes are required to be withheld from any amount
      payable to any such holder under this Guaranty Agreement or under the
      Notes, the amounts so payable to such holder shall be increased to the
      extent necessary to yield to such holder (after payment of all Foreign
      Taxes) interest or any such other amounts at the rates or in the amounts
      specified in the Note Agreements and the Notes.

9.    RANK OF GUARANTY. Each of the Special Guarantors agrees that its
      obligations under this Guaranty Agreement shall rank at least pari passu
      with all other unsecured senior obligations of such Special Guarantor now
      or hereafter existing.

10.   [SECTION INTENTIONALLY LEFT BLANK]


                                       6
<PAGE>

11.   REPRESENTATIONS AND WARRANTIES OF THE SPECIAL GUARANTORS.

      Each of the Special Guarantors represents and warrants as follows:

            (a) Organization, Good Standing and Location. Such Special Guarantor
      (and in the case of TEPPCO, its general partner) is (i) a corporation,
      limited partnership or limited liability company (as applicable) duly
      organized, validly existing and in good standing under the laws of its
      state of organization, (ii) duly qualified and authorized to do business
      and in good standing in every other jurisdiction where the nature of its
      business requires such qualification and (iii) has all requisite
      corporate, limited partnership or limited liability company (as
      applicable) power and authority, and all governmental licenses and
      permits, to own and operate its properties and to carry on its businesses
      as presently conducted. Such Special Guarantor has the requisite
      corporate, limited partnership or limited liability company (as
      applicable) power to enter into and perform its obligations under this
      Guaranty Agreement.

            (b) Approval and Enforceability of Guaranty Agreement. The
      execution, delivery and performance of this Guaranty Agreement has been
      duly authorized by all necessary corporate, partnership or limited
      liability company (as applicable) action on the part of such Special
      Guarantor (and in the case of TEPPCO, its general partner). The Guaranty
      Agreement has been duly and validly executed and delivered and constitutes
      the legal, valid and binding obligation of such Special Guarantor,
      enforceable against it in accordance with its terms.

            (c) Actions Pending. There is no action, suit, investigation or
      proceeding pending or, to the knowledge of such Special Guarantor (or, in
      the case of TEPPCO, to the knowledge of its general partner), threatened
      against such Special Guarantor or any of its Subsidiaries, or any
      properties or rights of such Special Guarantor or any of its Subsidiaries,
      by or before any court, arbitrator or administrative or governmental body
      which could reasonably be expected to have a Material Adverse Effect.

            (d) Conflicting Agreements and Other Matters. Neither such Special
      Guarantor nor any of its Subsidiaries is a party to or otherwise subject
      to any contract or agreement or subject to any charter, limited
      partnership agreement, limited liability company agreement, other
      organizational document or other corporate, limited partnership or limited
      liability company (as applicable) restriction which could reasonably be
      expected to have a Material Adverse Effect. Neither the execution nor
      delivery of this Guaranty Agreement, nor fulfillment of nor compliance
      with the terms and provisions hereof, will conflict with, or result in a
      breach of the terms, conditions or provisions of, or constitute a default
      under, or result in any violation of, or result in the creation of any
      Lien upon any of the


                                       7
<PAGE>

      properties or assets of such Special Guarantor or any of its Subsidiaries
      pursuant to, the charter, bylaws, limited partnership agreement, limited
      liability company agreement, regulations or other organizational documents
      of such Special Guarantor or any of its Subsidiaries, any award of any
      arbitrator or any agreement (including any agreement with stockholders,
      partners or members), instrument, order, judgment, decree, statute, law,
      rule or regulation to which such Special Guarantor or any of its
      Subsidiaries is subject. Neither such Special Guarantor nor any of its
      Subsidiaries is a party to, or otherwise subject to any provision
      contained in, any instrument evidencing Indebtedness of such Special
      Guarantor or such Subsidiary, any agreement relating thereto or any other
      contract or agreement (including its charter, limited partnership
      agreement, limited liability company agreement or other organizational
      documents) which limits the amount of, or otherwise imposes restrictions
      on the incurring of, Indebtedness of such Special Guarantor represented by
      this Guaranty Agreement.

            (e) Governmental Consent. Neither the nature of such Special
      Guarantor or of any Subsidiary, nor any of their respective businesses or
      properties, nor any relationship between such Special Guarantor or any
      Subsidiary and any other Person, nor any circumstance in connection with
      the execution and delivery of this Guaranty Agreement is such as to
      require any authorization, consent, approval, exemption or other action by
      or notice to or filing with any court or administrative or governmental
      body (other than routine filings after the date of closing with the
      Securities and Exchange Commission and/or state Blue Sky authorities) in
      connection with the execution and delivery of this Guaranty Agreement or
      fulfillment of or compliance with the terms and provisions hereof.

            (f) Disclosure. This Guaranty Agreement, together with each other
      document, certificate or statement furnished to any holder of Notes by or
      on behalf of such Special Guarantor in connection herewith, does not
      contain any untrue statement of a material fact or omit to state a
      material fact necessary in order to make the statements contained herein
      and therein not misleading. There is no fact peculiar to such Special
      Guarantor or any of its Subsidiaries (and not applicable to the oil and
      gas industry generally) which materially adversely affects or in the
      future may (so far as such Special Guarantor can now foresee) materially
      adversely affect the business, property or assets, financial condition or
      operations of such Special Guarantor and its Subsidiaries and which has
      not been set forth in this Guaranty Agreement or in the other documents,
      certificates and statements furnished to the holders of Notes by or on
      behalf of such Special Guarantor prior to the date hereof in connection
      with the transactions contemplated hereby.

12.   [SECTION INTENTIONALLY LEFT BLANK]

13.   TERMINATION AND RELEASE. Subject to the provisions of Section 7, and
      except to the extent that any Special Guarantor's obligations arising
      hereunder prior to such time have not been fulfilled, this Guaranty
      Agreement shall


                                       8
<PAGE>

      terminate and each of the Special Guarantors shall be absolutely,
      unconditionally and irrevocably released and discharged of any and all
      obligations hereunder on (i) the Guaranty Termination Date, (ii)
      indefeasible payment in full of the Special Guaranteed Obligations and the
      termination of the Facility and the Commitment or (iii) the Special PEPL
      Event Date, whichever of the preceding events shall first occur.

14.   [SECTION INTENTIONALLY LEFT BLANK]

15.   NOTICES. Unless otherwise specifically provided herein, all notices,
      consents, directions, approvals, instructions, requests and other
      communications required or permitted by the terms hereof shall be in
      writing, and any such communication shall become effective when received,
      addressed in the following manner: (a) if to TEPPCO, to it at 2929 Allen
      Parkway, Suite 3200, Houston, TX 77019, Attention: Chief Executive
      Officer, (b) if to MAP, to it at 539 South Main Street, Findlay, OH 45840,
      Attention: Treasurer or (c) if to any holder of a Note, to the respective
      addresses set forth in the Purchaser Schedules to the Note Agreements;
      provided, however, that any such addressee may change its address for
      communications by notice given as aforesaid to the other parties hereto.

16.   CONSTRUCTION. The section and subsection headings in this Guaranty
      Agreement are for convenience of reference only and shall neither be
      deemed to be a part of this Guaranty Agreement nor modify, define, expand
      or limit any of the terms or provisions hereof. All references herein to
      numbered sections, unless otherwise indicated, are to sections of this
      Guaranty Agreement. Words and definitions in the singular shall be read
      and construed as though in the plural and vice versa, and words in the
      masculine, neuter or feminine gender shall be read and construed as though
      in either of the other genders where the context so requires.

17.   SEVERABILITY. If any provision of this Guaranty Agreement, or the
      application thereof to any person or circumstances, shall, for any reason
      or to any extent, be invalid or unenforceable, such invalidity or
      unenforceability shall not in any manner affect or render invalid or
      unenforceable the remainder of this Guaranty Agreement, and the
      application of that provision to other persons or circumstances shall not
      be affected but, rather, shall be enforced to the extent permitted by
      applicable law.

18.   SUCCESSORS. The terms and provisions of this Guaranty Agreement shall be
      binding upon and inure to the benefit of each of the Special Guarantors
      and the holders of the Notes from time to time and their respective
      permitted successors, transferees and assigns.

19.   ENTIRE AGREEMENT; AMENDMENT. This Guaranty Agreement expresses the entire
      understanding of the subject matter hereof; and all other understandings,
      written or oral, are hereby merged herein and superseded. No


                                       9
<PAGE>

      amendment of or supplement to this Guaranty Agreement, or waiver or
      modification of, or consent under, the terms hereof shall be effective
      unless in writing and signed by the party to be bound thereby.

20.   TERM OF GUARANTY AGREEMENT. Except if released in accordance with Section
      13 hereof, the Guaranty Agreement and all guarantees, covenants and
      agreements of each of the Special Guarantors contained herein shall
      continue in full force and effect and shall not be discharged until such
      time as all of the Special Guaranteed Obligations shall be paid or
      otherwise discharged in full.

21.   SURVIVAL. All warranties, representations and covenants made by each of
      the Special Guarantors herein or in any certificate or other instrument
      delivered by such Special Guarantor or on such Special Guarantor's behalf
      under this Guaranty Agreement shall be considered to have been relied upon
      by the holders of the Notes and shall survive the execution and delivery
      of this Guaranty Agreement, regardless of any investigation made by the
      holder of the Notes or on their behalf.

22.   FURTHER ASSURANCES. Each of the Special Guarantors hereby agrees to
      execute and deliver all such instruments and take all such action as the
      holders of the Notes may from time to time reasonably request in order to
      effectuate fully the purposes of this Guaranty Agreement.

23.   GOVERNING LAW. This Guaranty Agreement shall be governed by, construed and
      enforced in all respects in accordance with the laws of the State of New
      York applicable to contracts made and to be performed entirely therein,
      without regard to principles of conflicts of laws.

24.   SUBMISSION TO JURISDICTION. Each of the Special Guarantors hereby
      irrevocably submits itself to the nonexclusive jurisdiction of the Supreme
      Court of the State of New York, New York County, of the United States of
      America and to the jurisdiction of the United States District Court for
      the Southern District of New York, for the purpose of any suit, action or
      other proceeding arising out of, or relating to, this Guaranty Agreement
      or the subject matter hereof, and hereby waives, and agrees not to assert,
      by way of motion, as a defense or otherwise, in any such suit, action or
      proceedings, (i) any claim that it is not personally subject to the
      jurisdiction of the above-named courts for any reason whatsoever, that
      such suit, action or proceeding is brought in an inconvenient forum or
      that the venue of such suit, action or proceeding is improper and (ii) any
      right which it may have to a trial by a jury. Any and all service of
      process and any other notice in any such action, suit or proceeding shall
      be effective against such parties if given by registered or certified
      mail, return receipt requested, or by any other means or mail which
      requires a signed receipt, postage prepaid, mailed to such parties as
      herein provided in Section 15.

25.   FACSIMILE TRANSMISSION; COUNTERPARTS. This Guaranty Agreement may be
      executed and delivered by facsimile transmission, and may be


                                       10
<PAGE>

      executed in any number of counterparts, each of which shall be an
      original, but all of which together shall constitute one instrument.

26.   ADDITIONAL TERMS AND CONDITIONS OF THIS GUARANTY AGREEMENT. In addition to
      the other terms and conditions of this Guaranty Agreement, the execution,
      delivery and performance by the Special Guarantors of their respective
      obligations hereunder are made subject to, and in reliance on, and the
      holders of the Notes accept this Guaranty Agreement on, the agreements and
      statements set forth as follows:

            (a) this Guaranty Agreement constitutes Acceptable Credit Support
      for purposes of curing the Sponsor Default Event with respect to PEPL
      described in the recitals to this Guaranty Agreement; and

            (b) so long as this Guaranty Agreement shall be in full force and
      effect and valid and binding upon each of the Special Guarantors (and so
      long as no Special Guarantor shall have asserted otherwise in writing), no
      other Sponsor Default Event and no Event of Default shall arise or be
      deemed to have arisen based upon (i) any action taken or omitted to be
      taken by PEPL under any Note Document, including, but without limitation,
      the failure of PEPL to pay in whole or part, timely, or otherwise, any
      Credit Fee or other amount owed by it, or (ii) the occurrence of any other
      event or circumstance in relation to PEPL.

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<PAGE>

      IN WITNESS WHEREOF, each of the Special Guarantors has caused this
Guaranty Agreement to be duly executed and delivered as of the date and year
first above written.


                                      TE PRODUCTS PIPELINE COMPANY,
                                           LIMITED PARTNERSHIP

                                      By:   TEPPCO GP, Inc.,
                                            its sole general partner

                                            By: /s/ CHARLES H. LEONARD
                                               ---------------------------------
                                            Name:  Charles H. Leonard
                                            Title: Senior Vice President & Chief
                                                     Financial Officer


                                      MARATHON ASHLAND PETROLEUM LLC

                                      By: /s/ G. L. PEIFFER
                                          -----------------------------------
                                      Name:  G. L. Peiffer
                                      Title: Senior Vice President,
                                             Finance & Information Technology

AGREED TO AND ACKNOWLEDGED
(FOR PURPOSES OF SECTIONS 2 AND 26 HEREOF):

THE PRUDENTIAL INSURANCE COMPANY
  OF AMERICA

By:  /s/  BRIAN N. THOMAS
   -----------------------------
          Brian N. Thomas
          Vice President


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