Which lubricant is safe on rubber seals?
Which lubricant is safe on rubber seals?
Silicone grease on most rubbers, and a PTFE or fluorosilicone product on silicone rubber itself — petroleum products swell and destroy natural rubber and EPDM.
Elastomer compatibility is the whole question, and it is counterintuitive because the answers are almost inverted. Natural rubber and EPDM are hydrocarbon-based and are swelled and destroyed by hydrocarbon oils, so petroleum jelly on a car door seal or a plumbing O-ring is a slow way of wrecking it. Silicone grease is chemically unrelated to those rubbers and leaves them alone — but for the same reason it swells silicone rubber, so a silicone O-ring wants a PTFE or fluorosilicone product instead. Nitrile, by contrast, is fine with mineral oil and attacked by some other solvents. Where the seal is critical — a plumbing fitting, a diving regulator, a pressure vessel — the manufacturer names a compatible lubricant, and that name is the answer.
The options, ranked
| Option | Good at | Bad at |
|---|---|---|
| Silicone grease | Compatible with most elastomers, waterproof, stable across a wide temperature range, and the standard for O-rings and door seals. | Swells silicone rubber itself, and contaminates any surface that is to be painted or glued. |
| PTFE-based lubricant | The right choice where the seal is silicone rubber, and it leaves a dry film. | Less durable than grease on a heavily worked seal. |
| Rubber seal conditioner | Formulated for car door and boot seals to keep them supple and stop them freezing shut. | Needs reapplying seasonally. |
| Mineral oil, petroleum jelly or general spray | Nothing on natural rubber or EPDM. | Hydrocarbons are absorbed by these rubbers, which swell, soften and lose their sealing shape permanently. |
Technique that changes the outcome
- Identify the rubber before choosing: EPDM and natural rubber for door and window seals, nitrile for most oil-side O-rings, silicone for high-temperature seals
- Apply a thin film; excess collects grit and does no more good
- Clean the seal first, since grit under a lubricated seal grinds it
- Treat car door seals before winter so they do not freeze to the paint
What goes wrong
- Petroleum jelly or mineral oil on natural rubber or EPDM
- Silicone grease on silicone rubber
- Silicone anywhere near a surface that will be painted afterwards
Compiled practical guidance rather than a published standard. Product formulations vary by brand and market, so read the label — and where the work is structural, electrical or gas, the regulations that apply where you are govern rather than anything here.
Other lubricant questions
| For | Use |
|---|---|
| A bike chain | Wet lube for wet conditions, dry lube for dry and dusty ones, wax if you want the cleanest and lowest-friction option — and not a general penetrant. |
| A lock | A dry lubricant — powdered graphite or a PTFE spray. Oil and general penetrating sprays gum locks up and are the classic way to ruin one. |
| A squeaky door hinge | A drop of light machine oil or a smear of white lithium grease on the pin — and lift the pin out to clean it, which is usually the actual fix. |
| A seized bolt | A dedicated penetrant or a 50/50 acetone and automatic transmission fluid mix, plus time, heat cycles and shock — and anti-seize on reassembly. |
| A squeaky floor | Talc, graphite or powdered soapstone worked into the joint as a stopgap — the real fix is screwing the board down to the joist. |
| A sticky drawer | Paraffin wax or beeswax on wooden runners, dry PTFE on metal ones — and never oil on wood. |
| A garage door | White lithium grease or a garage-door lubricant on rollers, hinges, springs and bearings — and not on the track, which should be clean and dry. |
Common questions
- Which lubricant is safe on rubber seals?
- Silicone grease on most rubbers, and a PTFE or fluorosilicone product on silicone rubber itself — petroleum products swell and destroy natural rubber and EPDM.
- What should I avoid?
- Petroleum jelly or mineral oil on natural rubber or EPDM Silicone grease on silicone rubber Silicone anywhere near a surface that will be painted afterwards
Related pages
- Which lubricant should I use on a bike chain? Wet lube for wet conditions, dry lube for dry and dusty ones, wax if you want the cleanest and lowest-friction option — and not a general penetrant.
- Which lubricant should I use on a lock? A dry lubricant — powdered graphite or a PTFE spray. Oil and general penetrating sprays gum locks up and are the classic way to ruin one.
- Which lubricant stops a squeaky door hinge? A drop of light machine oil or a smear of white lithium grease on the pin — and lift the pin out to clean it, which is usually the actual fix.
- Which penetrating fluid frees a seized bolt? A dedicated penetrant or a 50/50 acetone and automatic transmission fluid mix, plus time, heat cycles and shock — and anti-seize on reassembly.
- What should I put on a squeaky floorboard? Talc, graphite or powdered soapstone worked into the joint as a stopgap — the real fix is screwing the board down to the joist.
- What should I put on a sticky drawer? Paraffin wax or beeswax on wooden runners, dry PTFE on metal ones — and never oil on wood.
- Which lubricant should I use on a garage door? White lithium grease or a garage-door lubricant on rollers, hinges, springs and bearings — and not on the track, which should be clean and dry.
Sources
- Typical range compiled from manufacturer specifications — At One Place