AGREEMENT AND SECOND AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.3

AGREEMENT AND SECOND AMENDMENT TO CREDIT AGREEMENT

THIS AGREEMENT AND SECOND AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of February 1, 2005, is made and entered into by and among LUFKIN INDUSTRIES, INC., a Texas corporation (the “Borrower”) and JPMORGAN CHASE BANK, NATIONAL ASSOCIATION (formerly known as JPMorgan Chase Bank) (“JPMCB”), as the Lender, as the Issuing Bank, and as the Administrative Agent under the Credit Agreement referred to below (JPMCB, in all such capacities, the “Bank”). The Borrower and the Bank are herein sometimes called the “Parties”.

Preliminary Statements.

1. The Parties entered into a Credit Agreement dated as of December 30, 2002, and an Agreement and First Amendment to Credit Agreement dated as of June 30, 2004 (such Credit Agreement, as so amended, the “Credit Agreement”). Unless defined herein, terms used herein which are defined in the Credit Agreement shall have the meanings therein ascribed to them.

2. On November 13, 2004, JPMorgan Chase Bank changed its name to JPMorgan Chase Bank, N.A.

3. The Borrower has asked the Bank to increase the ceiling on the aggregate LC Exposures of all Lenders under the Credit Agreement, and the Bank is willing to grant that extension upon the terms and conditions set forth in this Amendment.

Agreements.

NOW, THEREFORE, in consideration of the premises and for other good and valuable consideration, the receipt and sufficiency of which are acknowledged by the Parties, the Parties agree as follows:

1. Amendment of Section 2.04(b). The third sentence of Section 2.04(b) of the Credit Agreement is hereby amended to provide in its entirety as follows:

“A Letter of Credit shall be issued, amended, renewed or extended only if (and upon issuance, amendment, renewal or extension of each Letter of Credit the Borrower shall be deemed to represent and warrant that), after giving effect to such issuance, amendment, renewal or extension the aggregate LC Exposures of all the Lenders at that time shall not exceed $10,000,000 and the total Revolving Credit Exposure of all Lenders shall not exceed the total Commitments at that time.”

2. Conditions Precedent. This Amendment shall be effective as of the date set forth above, subject to the satisfaction, in a manner satisfactory to the Bank, of each of the following conditions precedent:

(a) The Bank shall have received counterparts of this Amendment, duly executed by each of the Parties.

(b) The Bank shall have received a certificate signed by a Financial Officer of the Borrower certifying that

(i) Since September 30, 2004, there has been no material adverse change in the assets, liabilities, financial condition, business or affairs of the Borrower other than as disclosed in writing to the Administrative Agent before the execution of this Amendment. Each such written disclosure shall be included in the definition of “Disclosed Matter” for purposes of the Credit Agreement and this Amendment. Since September 30, 2004, there has occurred no change, event, circumstance, or condition in or with respect to the assets, liabilities, financial condition, business or affairs or the Parent Company and its Subsidiaries, taken as a whole, which, individually or in the aggregate with all other such changes, events, circumstances and conditions occurring since September 30, 2004, could reasonably be expected to result in a Material Adverse Effect, except for Disclosed Matters;

(ii) The representations and warranties of the Borrower set forth in the Credit Agreement are true and correct (except to the extent such representations and warranties expressly relate solely to an earlier date);

(iii) The Borrower has no material domestic Subsidiary that has not executed and delivered to the Bank a Guaranty;

(iv) The Borrower has no material international Subsidiary that has not executed and delivered to the Bank a Guaranty; and

(v) No Default has occurred and is continuing.

(c) No Legal Bar. The effectiveness of this Amendment shall not violate any Legal Requirement applicable to the Bank.

3. Representations True; No Default. The Borrower represents and warrants to the Bank that

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4. Ratification. Except as expressly amended hereby, the Credit Agreement, as hereby amended, and the other Loan Documents are in all respects ratified and confirmed and are, and shall continue to be, in full force and effect. The Borrower hereby agrees and acknowledges that all of its liabilities and obligations under the Credit Agreement and the other Loan Documents remain in full force and effect as of the date of this Amendment and after giving effect to it.

5. Definitions and References. Unless otherwise defined herein, terms used herein which are defined in the Credit Agreement shall have the meanings therein ascribed to them. The term “Agreement” as used in the Credit Agreement and the term “Credit Agreement” as used in the other Loan Documents or any other instrument, document or writing furnished to the Bank by or on behalf of the Borrower shall mean the Credit Agreement as hereby amended.

6. Expenses; Additional Information. The Borrower shall pay to the Bank on demand all expenses (including reasonable counsel’s fees) incurred in connection with the preparation, reproduction, execution and delivery of this Amendment.

7. Severability. If any term or provision of this Amendment or the application thereof to any person or circumstances shall, to any extent, be deemed invalid or unenforceable, the remainder of this Amendment, or the application of such term or provision to persons or circumstances other than those as to which it is held invalid or unenforceable, shall not be affected thereby and this Amendment shall be valid and enforced to the fullest extent permitted by applicable law. Any provision of this Amendment that is prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective to the extent of such prohibition or unenforceability without invalidating the remaining portions thereof or affecting the validity or enforceability of such provision in any other jurisdiction and, to this end, the provisions of this Amendment are severable.

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8. Miscellaneous. This Amendment (a) shall be binding upon and inure to the benefit of the Parties and their respective successors, assigns, receivers and trustees (however, the Borrower may not assign its rights hereunder without the express prior written consent of the Bank); (b) may be modified or amended only by a writing signed by each of the Parties; (c) SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS (WITHOUT GIVING EFFECT TO THE CONFLICT OF LAWS PRINCIPLES) AND OF THE UNITED STATES OF AMERICA; (d) may be executed and delivered by facsimile, and may be executed in several counterparts, and by the Parties on separate counterparts, and each counterpart, when so executed and delivered, shall constitute an original agreement, and all such separate counterparts shall constitute but one and the same agreement, (e) embodies the entire agreement and understanding among the Parties with respect to the subject matter hereof and supersedes all prior agreements, consents and understandings relating to such subject matter, and (f) is a Loan Document. The headings herein shall be accorded no significance in interpreting this Amendment.

9. ENTIRE AGREEMENT

THIS AMENDMENT REPRESENTS THE FINAL AGREEMENT AMONG THE PARTIES AS TO THE SUBJECT MATTER HEREOF AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS AMONG THE PARTIES.

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IN WITNESS WHEREOF, the Parties have caused this Amendment to be executed by their respective duly authorized officers effective as of the date written above.