<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-12-12</periodOfReport>

    <issuer>
        <issuerCik>0000105132</issuerCik>
        <issuerName>WD 40 CO</issuerName>
        <issuerTradingSymbol>WDFC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001398352</rptOwnerCik>
            <rptOwnerName>Etchart Eric</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O:  WD-40 COMPANY</rptOwnerStreet1>
            <rptOwnerStreet2>9715 BUSINESSPARK AVENUE</rptOwnerStreet2>
            <rptOwnerCity>SAN DIEGO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92131</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>false</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2023-12-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>406</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6938</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <transactionDate>
                <value>2023-12-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>251</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7189</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents a restricted stock unit (&quot;RSU&quot;) award covering shares of Issuer's common stock granted in accordance with the Issuer's Directors' Compensation Policy and Election Plan adopted on October 5, 2023 (&quot;2023 Directors' Compensation Policy&quot;).  This RSU award, which was granted effective December 12, 2023 and had an aggregate fair market value of approximately $97,000 on such date, is the non-elective portion of annual director compensation and vests upon grant.</footnote>
        <footnote id="F2">Represents an elective RSU award covering shares of Issuer's common stock granted in accordance with the Issuer's 2023 Directors' Compensation Policy.  This RSU award, which was granted effective December 12, 2023 (&quot;Grant Date&quot;) and was in lieu of receiving cash for annual base compensation for directors, had an aggregate fair market value of approximately $60,000 on the Grant Date.  Unless as otherwise provided in the 2023 Directors' Compensation Policy, and subject to continuous service as a director, the RSU award vests 1/12th per month over one year commencing on the first day of the calendar month after the Grant Date.</footnote>
        <footnote id="F3">Represents: (i) 1,500 shares acquired via stock purchases by Reporting Owner, (ii) 5,438 vested RSUs treated as common stock equivalents, and (iii) 251 unvested RSUs.  Following termination of the Reporting Person's service as a director, vested RSUs will be settled with Issuer's common stock.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Ann T. Nguyen, attorney-in-fact for Eric Etchart</signatureName>
        <signatureDate>2023-12-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0508
4
2023-12-12
0000105132
WD 40 CO
WDFC
0001398352
Etchart Eric
C/O:  WD-40 COMPANY
9715 BUSINESSPARK AVENUE
SAN DIEGO
CA
92131
true
false
Common Stock
2023-12-12
4
A
0
406
A
6938
D
Common Stock
2023-12-12
4
A
0
251
A
7189
D
Represents a restricted stock unit ("RSU") award covering shares of Issuer's common stock granted in accordance with the Issuer's Directors' Compensation Policy and Election Plan adopted on October 5, 2023 ("2023 Directors' Compensation Policy").  This RSU award, which was granted effective December 12, 2023 and had an aggregate fair market value of approximately $97,000 on such date, is the non-elective portion of annual director compensation and vests upon grant.
Represents an elective RSU award covering shares of Issuer's common stock granted in accordance with the Issuer's 2023 Directors' Compensation Policy.  This RSU award, which was granted effective December 12, 2023 ("Grant Date") and was in lieu of receiving cash for annual base compensation for directors, had an aggregate fair market value of approximately $60,000 on the Grant Date.  Unless as otherwise provided in the 2023 Directors' Compensation Policy, and subject to continuous service as a director, the RSU award vests 1/12th per month over one year commencing on the first day of the calendar month after the Grant Date.
Represents: (i) 1,500 shares acquired via stock purchases by Reporting Owner, (ii) 5,438 vested RSUs treated as common stock equivalents, and (iii) 251 unvested RSUs.  Following termination of the Reporting Person's service as a director, vested RSUs will be settled with Issuer's common stock.
Ann T. Nguyen, attorney-in-fact for Eric Etchart
2023-12-13