<?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>0001941449</rptOwnerCik>
            <rptOwnerName>Burks Cynthia</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="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>886</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents fully vested RSUs treated as common stock equivalents.  Following termination of the Reporting Person's service as a director, the RSUs will be settled with Issuer's common stock.</footnote>
        <footnote id="F2">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.  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>
    </footnotes>

    <ownerSignature>
        <signatureName>Ann T. Nguyen, attorney-in-fact for Cynthia Burks</signatureName>
        <signatureDate>2023-12-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0508
4
2023-12-12
0000105132
WD 40 CO
WDFC
0001941449
Burks Cynthia
C/O WD-40 COMPANY
9715 BUSINESSPARK AVENUE
SAN DIEGO
CA
92131
true
false
Common Stock
2023-12-12
4
A
0
406
A
886
D
Represents fully vested RSUs treated as common stock equivalents.  Following termination of the Reporting Person's service as a director, the RSUs will be settled with Issuer's common stock.
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.  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.
Ann T. Nguyen, attorney-in-fact for Cynthia Burks
2023-12-13