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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-10-24</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001836841</rptOwnerCik>
            <rptOwnerName>LINDEMAN JEFFREY G</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>
            <isOfficer>true</isOfficer>
            <officerTitle>VP, Chief People, Cult. &amp; Cap.</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>false</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2023-10-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>150</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2891</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares withheld pursuant to mandatory provisions of Restricted Stock Unit (RSU) Award Agreement(s) in satisfaction of tax withholding obligations upon vesting of 428 RSUs.</footnote>
        <footnote id="F2">Total includes:  (i) 173 shares of restricted Common Stock received upon settlement of performance share units or PSUs, (ii) 1,370 unvested RSUs, and (iii) 543 shares held in the WD-40 Company Profit Sharing / 401(k) Plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Ann T. Nguyen, attorney-in-fact for Jeffrey G. Lindeman</signatureName>
        <signatureDate>2023-10-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0508
4
2023-10-24
0000105132
WD 40 CO
WDFC
0001836841
LINDEMAN JEFFREY G
C/O:  WD-40 COMPANY
9715 BUSINESSPARK AVE.
SAN DIEGO
CA
92131
true
VP, Chief People, Cult. & Cap.
false
Common Stock
2023-10-24
4
F
0
150
D
2891
D
Shares withheld pursuant to mandatory provisions of Restricted Stock Unit (RSU) Award Agreement(s) in satisfaction of tax withholding obligations upon vesting of 428 RSUs.
Total includes:  (i) 173 shares of restricted Common Stock received upon settlement of performance share units or PSUs, (ii) 1,370 unvested RSUs, and (iii) 543 shares held in the WD-40 Company Profit Sharing / 401(k) Plan.
Ann T. Nguyen, attorney-in-fact for Jeffrey G. Lindeman
2023-10-26