For faucet stems, cartridges and O-rings, Oatey’s Hercules 40610 is a 2-ounce petroleum-free silicone plumber’s grease rated to 400°F and safe on plastic and rubber parts, per Oatey. For pushing gasketed pipe joints together, use a pipe-gasket lubricant instead, such as Hercules Duck Butter 40501, which is water soluble. Check the faucet or fitting maker’s instructions for the lubricant it calls for.
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Start with the component or joint, then check the product. A lubricant’s broad plumbing label does not establish universal seal compatibility or drinking-water certification.
Choose the lubricant for the assembly
| Product | Documented type | Application to check | Important limit |
|---|---|---|---|
| Hercules 40610 | Silicone plumber’s grease, 2 ounces | Permitted moving parts and O-ring lubrication | No blanket compatibility or NSF 61 certification claim here |
| Hercules Duck Butter 40501 | Water-soluble pipe-gasket lubricant, 2 pounds | Permitted gasketed pipe assembly | Not automatically the lubricant for any coupling or valve |
Identify whether the task is lubricating a moving seal or assembling a gasketed pipe joint. A familiar brand name does not make the two products substitutes.
Hercules 40610: silicone grease for a permitted component
Choose 40610 when the component maker permits a silicone plumber’s grease for that seal or moving part. The current Oatey page (oatey.com) identifies its two-ounce package and states that it contains no petroleum products.
Skip it when the assembly requires another named lubricant, prohibits field lubrication or needs a certification not established for this exact product.
The checked standard new Amazon offer from Plumbing Specials showed stock. Its part-number field read 40610 and its model field included the same number.
The currently linked August 2017 submittal (media.oatey.com) lists valve and O-ring applications, but its approvals section says “Not applicable.” This guide therefore does not label 40610 NSF 61-certified.
Check Hercules 40610 silicone plumber’s grease on Amazon →
Hercules Duck Butter 40501: a gasket assembly product
Choose 40501 when the pipe-and-gasket system permits this water-soluble assembly lubricant. The maker describes Duck Butter (oatey.com) as a pipe lubricant for joining with specified gasket materials.
Skip it as a universal faucet grease or an automatic addition to every flexible coupling. Obtain the joint maker’s application instructions before using it.
The 2023 Oatey catalog (oatey.com) maps 40501 to two pounds and distinguishes it from the larger 40506 package. We visually checked that ordering table.
The checked standard new Amazon.com offer showed stock, with 40501 in both model and part-number fields. The maker’s larger-container photo does not change the selected retail package.
Check Hercules Duck Butter 40501 gasket lubricant on Amazon →
Read the seal material and service conditions together
“Rubber O-ring” is not a complete material specification. Identify the actual seal compound and the fluid, temperature and movement it will encounter.
The Parker O-Ring Handbook (maker page: www.parker.com/content/dam/Parker-com/Literature/O-Ring-Division-Literature/ORD-5700.pdf) separates compatibility by compound and substance. Its tables are a reason to check the exact combination, not permission to treat every black O-ring alike.
Use the component maker’s instructions for the actual assembly. A lubricant that is acceptable for one loose O-ring may not be permitted on a factory-prepared sealing component.
If the seal material or approved lubricant is unknown, obtain the part specification before applying a convenient product from the truck. Do not infer compatibility from the grease color or the O-ring color.
Do not transfer approval from a neighboring catalog product
Read the approval statement beside the exact model. A certification symbol elsewhere on the same catalog page should not be assigned to every grease shown there.
The Oatey catalog page groups Duck Butter, silicone grease and other lubricants together. The products retain separate descriptions and approval information.
For a drinking-water application, confirm the exact current listing and its permitted use conditions as well as the component maker’s acceptance. A general “plumbing” or “waterproof” label is not the same thing.
This guide does not turn an old catalog mark into current blanket approval for a particular installed system. Keep the current exact product documentation with any required submittal.
Gasketed bell joints and flexible couplings need separate instructions
A pipe lubricant sold for gasket assembly does not establish the preparation method for every kind of joint. Identify the joint design and its actual manufacturer.
Our no-hub versus flexible coupling guide covers different coupling arrangements. The selected gasket, pipe surfaces, shield and clamps still need their own instructions.
Do not add grease simply because a joint is difficult to assemble. Check correct sizing, alignment, gasket condition and the prescribed assembly method first.
No universal coupling lubrication, insertion force or clamp torque is given here. Those details belong to the exact joint system rather than a general-purpose lubricant comparison.
Lubricant is not a substitute for the intended seal
Determine how the joint is designed to seal. An O-ring, a compression gasket, a tapered thread and a caulked surface are different mechanisms.
Do not use grease to disguise a damaged, incorrectly sized or missing sealing component. Identify the cause of leakage or binding before deciding whether lubrication is part of the repair.
A lubricant can have a role in assembly or movement where the instructions permit it. That does not make it a universal leak-stopping compound.
Likewise, avoid placing it on another surface merely because it is nearby. Keep lubrication confined to the permitted parts and application method.
Keep grease separate from tape, pipe compound and putty
Read our tape, pipe compound and putty comparison when the task concerns sealing rather than lubrication.
A tube of silicone grease is not silicone sealant. Similar words on a label can describe products with very different purposes and assembly behavior.
Also distinguish a lubricant for a gasketed bell joint from solvent cement used in a different pipe connection. Do not mix products or copy preparation steps between those methods.
Before opening a container, write down the joint or component, exact product and reason it is permitted. That simple record makes a substitute easier to detect before it enters the assembly.
Use the current instructions and keep the container clean
The linked 40610 safety sheet (media.oatey.com) identifies the exact product and handling information. Read the current label, safety sheet and assembly instructions together before use.
Keep products in their labeled containers and avoid introducing grit or mixing residues from another lubricant. A shared dirty applicator can undermine an otherwise correct product choice.
Use the amount and location the component maker specifies. This page does not prescribe a universal thin film, liberal coating or relubrication interval for every valve and gasket.
Clean up unintended residue according to the applicable instructions. A spill or smear on a walking surface is a different problem from lubricant deliberately applied inside a permitted assembly.
Choose the product after confirming the joint
For a permitted moving component or O-ring application, compare the exact silicone-grease requirements with 40610. For a permitted gasketed pipe assembly, compare the exact joint requirements with Duck Butter 40501.
Neither is ranked as the universal winner. They address different work, and the small grease container and larger pipe-lubricant tub are not directly comparable kit quantities.
Check the full model number, package size and current seller before ordering. Do not substitute the petroleum-based 40601 merely because its number looks similar to 40610.
We did not measure seal life, friction, assembly force or washout. The useful result is a clearly identified product choice backed by the actual assembly’s permission.
Frequently asked questions
Are silicone grease and silicone sealant the same product?
No. Check the exact label and intended role; a lubricant is not a general substitute for a sealing compound.
Is Hercules 40610 described here as NSF 61-certified?
No. Its currently linked submittal lists approvals as not applicable. Verify any required current certification for the exact product and use.
Is Duck Butter 40501 a two-pound or larger package?
The cited maker ordering table identifies 40501 as two pounds and distinguishes the larger 40506 package.
Can any plumber’s grease be used on any O-ring?
No universal compatibility is established. Identify the seal compound, service conditions and component maker’s permitted lubricant.
Should gasket lubricant automatically be added to a no-hub coupling?
No generic instruction is given. Follow the exact coupling and gasket maker’s assembly requirements.
How we chose
This document-based comparison makes no hands-on testing claim. We checked current Oatey product pages, its currently linked 40610 submittal and safety sheet, and the manufacturer’s 2023 catalog. We visually checked the submittal approval section and the catalog product table. On October 14, 2026, both linked standard new Amazon offers showed stock with matching identity fields. We did not test friction, seal life, washout or assembly force. Read our selection method and about Plumbing Picks.
Primary sources
- Hercules 40610 current maker page (oatey.com): silicone-grease identity, two-ounce size and no-petroleum statement.
- Currently linked 40610 submittal, August 2017 (media.oatey.com): applications and approvals section visually checked; no NSF 61 certification asserted.
- Hercules 40610 safety sheet, September 2021 (media.oatey.com): exact product identification and handling information.
- Hercules Duck Butter current maker page (oatey.com): water-soluble gasketed-pipe lubricant role.
- Oatey 2023 catalog, page 83 (oatey.com): 40501 two-pound package and separate lubricant descriptions; table visually checked.
- Parker O-Ring Handbook (maker page: www.parker.com/content/dam/Parker-com/Literature/O-Ring-Division-Literature/ORD-5700.pdf): compound-specific compatibility framework, not approval for either linked product on every seal.