Exhibit 10.1

SUPPLEMENT AGREEMENT

THIS SUPPLEMENT AGREEMENT (this "Agreement") dated as of December 22, 2008, is being executed and delivered pursuant to that certain Second Amended and Restated Revolving Credit Agreement, dated as of December 21, 2006, as amended by the First Amendment to Second Amended and Restated Revolving Credit Agreement, dated as of September 26, 2008 (as amended, restated, supplemented or otherwise modified from time to time, the "Credit Agreement"), among NEWMARKET CORPORATION, a Virginia corporation, as Borrower, the Lenders from time to time party thereto, PNC Bank, National Association, in its capacity as Documentation Agent for the Lenders, General Electric Capital Corporation and Bank of America, N.A., in their capacities as Co-Syndication Agents for the Lenders, and SUNTRUST BANK, as Administrative Agent, as issuing bank and as swingline lender, by SUNTRUST BANK (the "Increasing Lender") and the Borrower, and accepted by the Administrative Agent. Capitalized terms used herein and not otherwise defined herein shall have the meanings assigned to such terms in the Credit Agreement.

RECITALS

A. Pursuant to Section 2.23 of the Credit Agreement, the Borrower has notified the Administrative Agent and each of the Lenders that the Borrower proposes to increase the Aggregate Revolving Commitments under the Credit Agreement by the amount of $7,000,000 provided, however, that at no time shall the Aggregate Commitments exceed the unsubscribed amount of the Additional Commitment Amount.

B. The Increasing Lender has agreed to increase its Commitment to the amount specified for it on Schedule I attached to this Agreement.

C. The parties to this Agreement are entering into this Agreement for purposes of effecting the increase in the Commitment of the Increasing Lender, as contemplated by Section 2.23 of the Credit Agreement.

Accordingly, each of the parties to this Agreement hereby agrees as follows:

1. The Increasing Lender hereby agrees to increase the amount of its Commitment to the Borrower under the Credit Agreement to the amount shown as being its increased Commitment amount on Schedule I attached to this Agreement. Such increase shall take effect for all purposes of the Credit Agreement on the Effective Date (as hereinafter defined) of this Agreement.

2. Each party hereto acknowledges and agrees that the Commitments of the Increasing Lender and the other Lenders under the Credit Agreement are several and not joint commitments and obligations of such Lenders. After giving effect to the increased Commitment as provided in this Agreement, each party further acknowledges and agrees that (i) the Commitments in effect for all Lenders under the Credit Agreement shall be those shown on Schedule II attached to this Agreement, (ii) Schedule II attached to the Credit Agreement shall be amended and restated as set forth on Schedule II attached to this Agreement, and (iii) upon any increase in the aggregate amount of the Revolving Commitments that is not pro rata among all Lenders, any and all Base Rate Loans and Eurodollar Loans, and any and all Letters of Credit that are outstanding under the Credit Agreement on the Effective Date shall be subject to the provisions of Section 2.23(e) of the Credit Agreement.

3. Each party hereto agrees that this Agreement and the effectiveness of the increased Commitment as provided in this Agreement shall be subject to satisfaction by the Borrower of the following conditions and requirements:

(a) The Borrower shall have delivered to the Administrative Agent the following in form and substance satisfactory to the Administrative Agent:

(i) a counterpart of this Agreement signed by the Increasing Lender, the Borrower and the Administrative Agent;

(ii) a duly executed Revolving Credit Note payable to the Increasing Lender to the extent requested by the Increasing Lender; and

(iii) a certification on behalf of the Borrower as of the Effective Date of this Agreement that (x) no Default or Event of Default then exists, (y) all representations and warranties of the Borrower set forth in the Credit Agreement are true and correct in all material respects on such date (or, if any such representation or warranty is expressly stated to have been made as of a specific date, as of such specific date), and (z) since the date of the financial statements of the Borrower described in Section 5.1 of the Credit Agreement, there has been no change which has had or could reasonably be expected to have a Material Adverse Effect.

(b) The Borrower shall have paid to the Increasing Lender a fee equal to 2.00% of the increase in Commitment of the Increasing Lender.

(c) The Borrower shall have paid to the Administrative Agent all costs and expenses incurred by the Administrative Agent in connection with this Supplement Agreement and the transactions contemplated herein, including without limitation, all reasonable fees and expenses of counsel for the Administrative Agent.

The date on which the foregoing conditions have been satisfied shall be the "Effective Date" of this Agreement.

4. The Borrower represents and warrants to the Administrative Agent and the Lenders that this Agreement has been duly authorized, executed and delivered by the Borrower, and that the Credit Agreement, as supplemented and amended hereby, constitutes the legal, valid and binding obligation of the Borrower enforceable against the Borrower in accordance with its terms except as may be limited by applicable bankruptcy, insolvency, reorganization, moratorium, or similar laws affecting the enforcement of creditors' rights generally and by general principles of equity.

5. The Administrative Agent and Required Lenders have waived the thirty (30) days' written notice requirement of Section 2.23(a) of the Credit Agreement.

6. Except as supplemented and amended hereby, the Credit Agreement and all other documents executed in connection therewith shall remain in full force and effect. The Credit Agreement, as supplemented and amended hereby, and all rights, powers and obligations created thereby or thereunder and under the Loan Documents and all such other documents executed in connection therewith are in all respects ratified and confirmed.

7. This Agreement may be executed in multiple counterparts, each of which shall constitute an original but all of which when taken together shall constitute one contract. This Agreement constitutes the entire agreement among the parties hereto regarding the subject matter hereof and supersedes all prior agreements and understandings, oral or written, regarding such subject matter.

8. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

IN WITNESS WHEREOF, the Increasing Lender and the Borrower have caused this Agreement to be duly executed and delivered by their respective authorized officers and representatives, and the Administrative Agent, for the benefit of the Increasing Lender, and all other Lenders under the Credit Agreement, has caused the same to be accepted by its authorized officer, as of the day and year first above written.

SUNTRUST BANK,

as Increasing Lender

By: /s/ Mark A. Flatin

Name: Mark A. Flatin

Title: Managing Director

NEWMARKET CORPORATION,

as Borrower

By: /s/ David A. Fiorenza

Name: David A. Fiorenza

Title: Vice President, Treasurer and Principal Financial Officer

ACCEPTED THIS 22^nd

DAY OF DECEMBER, 2008:

SUNTRUST BANK,

as Administrative Agent

By: /s/ Mark A. Flatin

Name: Mark A. Flatin

Title: Managing Director

ACKNOWLEDGMENT AND AGREEMENT

The undersigned, NEWMARKET CORPORATION, as Borrower and each of the subsidiaries of the Borrower listed on Schedule A hereto (each a "Guarantor" and collectively the "Guarantors") acknowledge the execution, delivery and effectiveness of the foregoing Supplement Agreement dated as of December 22, 2008 (the "Agreement") entered into pursuant to the terms of that certain Second Amended and Restated Revolving Credit Agreement, dated as of December 21, 2006, as amended by the First Amendment to Second Amended and Restated Revolving Credit Agreement, dated as of September 26, 2008 (as amended, restated, supplemented or otherwise modified from time to time, the "Credit Agreement"), and hereby acknowledge, confirm and agree as follows: (i) the Amended and Restated Subsidiary Guaranty Agreement, dated as of December 21, 2006, previously executed and delivered by the undersigned in respect of the obligations of the Borrower pursuant to the Credit Agreement remains in full force and effect on and after the date hereof, after giving effect to the increased Revolving Commitment as provided in the Agreement, (ii) the Obligations as provided in such Amended and Restated Subsidiary Guaranty Agreement shall include, without limitation, all borrowings and other extensions of credit made pursuant to the Revolving Commitments as so supplemented and increased, and (iii) nothing contained in the Agreement shall in any way be deemed to limit, discharge, release or otherwise affect the obligations and liabilities of the undersigned pursuant to such Amended and Restated Subsidiary Guaranty Agreement, all of which obligations and liabilities remain in full force and effect as provided therein and herein.

This Acknowledgment and Agreement made and entered into effective as of December 22, 2008.

[Signature Pages Follow]

NEWMARKET CORPORATION

By: /s/ David A. Fiorenza

Name: David A. Fiorenza

Title: Vice President, Treasurer and

Principal Financial Officer

Afton Chemical Additives Corporation

By: /s/ M. Rudolph West

Name: M. Rudolph West

Title: Secretary and Treasurer

Afton Chemical Asia Pacific LLC

By: /s/ Robert A. Shama

Name: Robert A. Shama

Title: Manager

Afton Chemical Canada Holdings, Inc.

By: /s/ M. Rudolph West

Name: M. Rudolph West

Title: Secretary and Treasurer

Afton Chemical Corporation

By: /s/ David A. Fiorenza

Name: David A. Fiorenza

Title: Treasurer

Afton Chemical Japan Holdings, Inc.

By: /s/ M. Rudolph West

Name: M. Rudolph West

Title: Secretary and Treasurer

AFTON CHEMICAL INTANGIBLES LLC

By: /s/ C.S. Warren Huang

Name: C.S. Warren Huang

Title: Manager

THE EDWIN COOPER CORPORATION

By: /s/ M. Rudolph West

Name: M. Rudolph West

Title: Secretary

Ethyl Asia Pacific LLC

By: /s/ Wayne C. Drinkwater

Name: Wayne C. Drinkwater

Title: Manager

Ethyl Canada Holdings, Inc.

By: /s/ M. Rudolph West

Name: M. Rudolph West

Title: Secretary and Treasurer

ETHYL CORPORATION

By: /s/ Wayne C. Drinkwater

Name: Wayne C. Drinkwater

Title: Vice President and Treasurer

ETHYL EXPORT CORPORATION

By: /s/ M. Rudolph West

Name: M. Rudolph West

Title: Secretary and Treasurer

Ethyl Interamerica Corporation

By: /s/ M. Rudolph West

Name: M. Rudolph West

Title: Secretary and Treasurer

ETHYL VENTURES, INC.

By: /s/ M. Rudolph West

Name: M. Rudolph West

Title: Secretary and Treasurer

Interamerica Terminals Corporation

By: /s/ M. Rudolph West

Name: M. Rudolph West

Title: Secretary and Treasurer

NewMarket Investment Company

By: /s/ David A. Fiorenza

Name: David A. Fiorenza

Title: Vice President and Treasurer

NEWMARKET SERVICES CORPORATION

By: /s/ David A. Fiorenza

Name: David A. Fiorenza

Title: Vice President and Principal Financial Officer

OLD TOWN LLC

By: /s/ Bruce R. Hazelgrove, III

Name: Bruce R. Hazelgrove, III

Title: Manager

Schedule A

to

Acknowledgement and Agreement to Supplement Agreement

Guarantor(s)

Address

Afton Chemical Additives Corporation Afton Chemical Asia Pacific LLC Afton Chemical Canada Holdings, Inc. Afton Chemical Corporation Afton Chemical Japan Holdings, Inc. Afton Chemical Intangibles LLC The Edwin Cooper Corporation Ethyl Asia Pacific LLC Ethyl Canada Holdings, Inc. Ethyl Corporation Ethyl Export Corporation Ethyl Interamerica Corporation Ethyl Ventures, Inc. Interamerica Terminals Corporation NewMarket Investment Company NewMarket Services Corporation Old Town LLC

330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219 330 South 4th Street, Richmond, Virginia 23219

Schedule I

INCREASED REVOLVING COMMITMENT

Increasing Lender	Increased Revolving Commitment
SunTrust Bank	$7,000,000

Schedule II

COMMITMENT AMOUNTS

Lender	Revolving Commitment Amount	Pro Rata Share
SunTrust Bank	$34,000,000	31.77%
Bank of America, N.A.	$21,000,000	19.63%
General Electric Capital Corporation	$21,000,000	19.63%
PNC Bank, National Association	$21,000,000	19.63%
RZB Finance LLC	$10,000,000	9.34%
TOTAL	$107,000,000

*Effective as of December 22, 2008.