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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2024-10-03</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>2024-10-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1177</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3853</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2024-10-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>677</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4530</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2024-10-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>144</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4660</value>
                    <footnoteId id="F4"/>
                </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, as amended and restated effective December 12, 2023.  Except as otherwise provided in the RSU award agreement, the RSUs vest annually over 3 years.</footnote>
        <footnote id="F2">Represents the vesting of market share units (MSUs) upon certification of market performance achieved.  The 3-year performance cliff vesting MSUs were granted on October 12, 2021 under the WD-40 Company 2016 Stock Incentive Plan and will be settled with Issuer's Common Stock on the date provided for in the MSU award agreement.</footnote>
        <footnote id="F3">Represents the vesting of performance stock units (PSUs) upon certification of fiscal year 2024 performance achieved.  The PSUs were granted on October 5, 2023 under the WD-40 Company 2016 Stock Incentive Plan and will be settled with Issuer's restricted Common Stock on the date provided for in the PSU award agreement.  Reporting Person may not sell such restricted stock before termination of employment.</footnote>
        <footnote id="F4">Total includes:  (i) 3,046 unvested RSUs (which include the grant of RSUs reported in this Form 4), (ii) 677 shares of Common Stock to be received upon settlement of MSUs, (iii) 144 shares of restricted Common Stock to be received upon settlement of PSUs, and (iv) 355 shares held in Reporting Person's WD-40 Company Profit Sharing / 401(k) Plan account.  The current balance in the 401(k) account reflects a net reduction of 15 shares from the previously reported balance (370 shares) for the following stock activity:  (a) on May 28, 2024, the 401(k) plan administrator unilaterally liquidated WDFC shares valued at approximately $4,000 to return excess 401(k) contributions for tax year 2023 to Reporting Person, and (b) from July 2023 through July 2024, Reporting Person received quarterly stock dividends.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Ann T. Nguyen, attorney-in-fact for Sara K. Hyzer</signatureName>
        <signatureDate>2024-10-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0508
4
2024-10-03
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
2024-10-03
4
A
0
1177
A
3853
D
Common Stock
2024-10-03
4
A
0
677
A
4530
D
Common Stock
2024-10-03
4
A
0
144
A
4660
D
Represents a grant of restricted stock units (RSUs) under the WD-40 Company 2016 Stock Incentive Plan, as amended and restated effective December 12, 2023.  Except as otherwise provided in the RSU award agreement, the RSUs vest annually over 3 years.
Represents the vesting of market share units (MSUs) upon certification of market performance achieved.  The 3-year performance cliff vesting MSUs were granted on October 12, 2021 under the WD-40 Company 2016 Stock Incentive Plan and will be settled with Issuer's Common Stock on the date provided for in the MSU award agreement.
Represents the vesting of performance stock units (PSUs) upon certification of fiscal year 2024 performance achieved.  The PSUs were granted on October 5, 2023 under the WD-40 Company 2016 Stock Incentive Plan and will be settled with Issuer's restricted Common Stock on the date provided for in the PSU award agreement.  Reporting Person may not sell such restricted stock before termination of employment.
Total includes:  (i) 3,046 unvested RSUs (which include the grant of RSUs reported in this Form 4), (ii) 677 shares of Common Stock to be received upon settlement of MSUs, (iii) 144 shares of restricted Common Stock to be received upon settlement of PSUs, and (iv) 355 shares held in Reporting Person's WD-40 Company Profit Sharing / 401(k) Plan account.  The current balance in the 401(k) account reflects a net reduction of 15 shares from the previously reported balance (370 shares) for the following stock activity:  (a) on May 28, 2024, the 401(k) plan administrator unilaterally liquidated WDFC shares valued at approximately $4,000 to return excess 401(k) contributions for tax year 2023 to Reporting Person, and (b) from July 2023 through July 2024, Reporting Person received quarterly stock dividends.
Ann T. Nguyen, attorney-in-fact for Sara K. Hyzer
2024-10-07