<?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>0001951273</rptOwnerCik>
            <rptOwnerName>HYZER SARA KATHLEEN</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, Finance &amp; CFO</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>168</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2474</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 481 RSUs.</footnote>
        <footnote id="F2">Total includes 1,868 unvested RSUs and 168 shares held in the WD-40 Company Profit Sharing / 401(k) Plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Ann T. Nguyen, attorney-in-fact for Sara K. Hyzer</signatureName>
        <signatureDate>2023-10-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0508
4
2023-10-24
0000105132
WD 40 CO
WDFC
0001951273
HYZER SARA KATHLEEN
C/O: WD-40 COMPANY
9715 BUSINESSPARK AVE.
SAN DIEGO
CA
92131
true
VP, Finance & CFO
false
Common Stock
2023-10-24
4
F
0
168
D
2474
D
Shares withheld pursuant to mandatory provisions of Restricted Stock Unit (RSU) Award Agreement(s) in satisfaction of tax withholding obligations upon vesting of 481 RSUs.
Total includes 1,868 unvested RSUs and 168 shares held in the WD-40 Company Profit Sharing / 401(k) Plan.
Ann T. Nguyen, attorney-in-fact for Sara K. Hyzer
2023-10-26