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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-10-05</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001691913</rptOwnerCik>
            <rptOwnerName>Brass Steven A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O:  WD-40 COMPANY</rptOwnerStreet1>
            <rptOwnerStreet2>9715 BUSINESSPARK AVE.</rptOwnerStreet2>
            <rptOwnerCity>SAN DIEGO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92131</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>true</isOfficer>
            <officerTitle>President and CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>false</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2023-10-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4451</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20984</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents a grant of restricted stock units (RSUs) under the WD-40 Company 2016 Stock Incentive Plan.  Except as otherwise provided in the RSU award agreement, the RSUs vest annually over 3 years.</footnote>
        <footnote id="F2">Total includes: (i) 973 shares of restricted Common Stock received upon settlement of performance share units or PSUs, (ii) 10,008 unvested RSUs, (iii) 108 vested deferred performance units or DPUs, which are Common Stock equivalents, and (iv) 1,776 shares held in the WD-40 Company Profit Sharing / 401(k) Plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Ann T. Nguyen, attorney-in-fact for Steven A. Brass</signatureName>
        <signatureDate>2023-10-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0508
4
2023-10-05
0000105132
WD 40 CO
WDFC
0001691913
Brass Steven A
C/O:  WD-40 COMPANY
9715 BUSINESSPARK AVE.
SAN DIEGO
CA
92131
true
true
President and CEO
false
Common Stock
2023-10-05
4
A
0
4451
A
20984
D
Represents a grant of restricted stock units (RSUs) under the WD-40 Company 2016 Stock Incentive Plan.  Except as otherwise provided in the RSU award agreement, the RSUs vest annually over 3 years.
Total includes: (i) 973 shares of restricted Common Stock received upon settlement of performance share units or PSUs, (ii) 10,008 unvested RSUs, (iii) 108 vested deferred performance units or DPUs, which are Common Stock equivalents, and (iv) 1,776 shares held in the WD-40 Company Profit Sharing / 401(k) Plan.
Ann T. Nguyen, attorney-in-fact for Steven A. Brass
2023-10-10