The best vacuum grease keeps seals tight and helps stop air leaks.
It works on O-rings, glass joints, and other vacuum gear.
Different formulas suit different jobs, from lab setups to general sealing.
Here are nine solid picks, including Molykote, Dow Corning, Super Lube, and SG01A.
More Details on Our Top Picks
Molykote High Vacuum Silicone Grease Tube (5.3 oz)
Best Overall
Check Latest PriceIf you need a vacuum grease that can handle tough sealing jobs without turning messy or breaking down, the Molykote High Vacuum Silicone Grease Tube is a strong pick for you. You get a high-purity silicone formula that stays put, cuts friction, and resists wear. It seals O-rings, valves, joints, and plastic parts with steady adhesion. Because it’s waterproof and chemical resistant, it won’t wash away easily. It also works from -40°F to 400°F, so you can trust it in cold spaces, hot equipment, and even electrical connections.
- Form:Grease
- Silicone-based:Silicone
- Tube/Container:Tube
- Vacuum Use:High vacuum
- Water Resistant:Waterproof
- Temperature Stability:-40°F to 400°F
- Additional Feature:Food-grade NSF approved
- Additional Feature:FDA compliant formula
- Additional Feature:Protects electrical connections
Dow Corning Vacuum Lubricant 5.3oz Tube
Heavy-Duty Seal
Check Latest PriceDow Corning Vacuum Lubricant 5.3oz Tube is a smart pick for you should you need a grease that seals well, stays stable, and keeps working in tough conditions without fuss. You get a silicon-based lubricant with strong sealing power, low volatility, and solid resistance to water, chemicals, heat, and cold. It works well on rubber gaskets, O-rings, and vacuum gear like binoculars and telescopes. Because it stays oxidation stable and has a 300 degrees Celsius flash point, you can trust it in demanding setups. The 5.3 ounce tube makes application easy and tidy for everyday maintenance.
- Form:Grease
- Silicone-based:Silicon-based
- Tube/Container:Tube
- Vacuum Use:Vacuum lubricant
- Water Resistant:Water resistant
- Temperature Stability:High/low temp
- Additional Feature:Strong sealing ability
- Additional Feature:Oxidation stable
- Additional Feature:Chemical processing equipment
Dow Corning High Vacuum Grease Lubricant 1/2 oz
Precision Pick
Check Latest PriceThis compact 1/2 oz bottle is a smart pick for you whenever you need a grease that stays steady under tough conditions and won’t degrade when the job gets serious. Dow Corning’s high vacuum grease uses a silicone base with low vapor pressure, so it helps you seal and protect parts in demanding spaces. It stays stiff and nonmelting from -40°C to 204°C, which gives you confidence in hot or cold work. You can use it on precision equipment, machine parts, and high vacuum systems, and it resists oxidation and chemicals too.
- Form:Grease
- Silicone-based:Silicone-based
- Tube/Container:Bottle
- Vacuum Use:High vacuum
- Water Resistant:Water resistant
- Temperature Stability:-40°C to 204°C
- Additional Feature:Low vapor pressure
- Additional Feature:Stiff nonmelting formula
- Additional Feature:Precision equipment lubrication
Super Lube 91003 Silicone High-Dielectric and Vacuum Grease 3 oz.
Best For Electronics
Check Latest PriceSuper Lube 91003 Silicone High-Dielectric and Vacuum Grease, 3 oz., is a smart pick for anyone who needs one grease that can handle both electrical and vacuum jobs with confidence. You can use it on bulb bases, battery terminals, brake parts, and vacuum seals, so one tube does a lot. Its silicone formula stays noncuring, so it won’t harden or dry out. It also blocks water, heat, and moisture, while guarding rubber and metal parts. Plus, its NSF H1 rating makes it welcome in food areas too.
- Form:Grease
- Silicone-based:Silicone compound
- Tube/Container:Tube
- Vacuum Use:Vacuum systems
- Water Resistant:Waterproof
- Temperature Stability:Heat resistant
- Additional Feature:High-dielectric insulation
- Additional Feature:NSF H1 registered
- Additional Feature:Won’t harden dry
SG01A High Vacuum Grease 3oz (85g)
Best Budget
Check Latest PriceShould you need a compact grease that handles both vacuum sealing and electrical insulation, SG01A High Vacuum Grease stands out as a smart pick for you. EDSRDUS makes this silicone paste in a 3 ounce can, and its thick SAE 60 feel helps it stay where you apply it. You can use it for O-rings, vacuum pumps, glass pistons, and marine electrical points. It also works as a dielectric, waterproof grease, so you get extra peace of mind. Because it’s small and easy to handle, you can keep your seal work neat, steady, and less messy too.
- Form:Paste
- Silicone-based:Silicone
- Tube/Container:Can
- Vacuum Use:Vacuum pump
- Water Resistant:Waterproof
- Temperature Stability:Not stated
- Additional Feature:SAE 60 viscosity
- Additional Feature:Electrical insulation use
- Additional Feature:Glass piston use
Molykote High Vacuum Grease 150g Silicone Lubricant
Premium Formula
Check Latest PriceMolykote High Vacuum Grease 150g Silicone Lubricant is the right pick should you need a tough seal that won’t quit in vacuum or pressure systems, because its stiff silicone formula grips O-rings, valves, and packings with steady confidence. You also get strong water and chemical resistance, so you can trust it around harsh process gear. Its low volatility helps it stay put, while the broad temperature range supports hot and cold jobs. You can use it on bearings, rubber seals, and optical lenses too, since it helps prevent fogging. The 150g tube gives you plenty for careful, messy-free work.
- Form:Silicone lubricant
- Silicone-based:Silicone
- Tube/Container:Tube
- Vacuum Use:High vacuum
- Water Resistant:Water resistant
- Temperature Stability:-40°C to 204°C
- Additional Feature:No intentional PTFE
- Additional Feature:No intentional PFAS
- Additional Feature:Prevents optical fogging
High Vacuum Sealing Grease for Lab Ground Glass Joint Seal and Lubrication
Best For Labs
Check Latest PriceWhenever you work with fragile lab glassware and need a seal that stays steady under real vacuum conditions, DONLAB High Vacuum Sealing Grease is made for you. You can use it on ground glass joints, stopcocks, flanges, and separatory funnels with confidence. It handles vacuum down to 6.5 × 10⁻⁵ Pa, so your setup stays tight. It also works from -54 ℃ to +200 ℃, which helps whenever heat or cold shifts. Because it won’t corrode rubber or plastic, you can protect more parts. Clean, dry, then apply a thin layer for smooth sealing.
- Form:Grease
- Silicone-based:Silicone oil
- Tube/Container:Tube
- Vacuum Use:Vacuum sealing
- Water Resistant:Water resistant
- Temperature Stability:-54°C to 200°C
- Additional Feature:Vacuum degree 6.5×10⁻⁵ Pa
- Additional Feature:Good electrical insulation
- Additional Feature:Lab ground-glass joints
SG01A High Vacuum Silicone Grease Lubricant 8oz
Best Versatility
Check Latest PriceSG01A High Vacuum Silicone Grease Lubricant 8oz is a smart pick whenever you need one grease that can handle sealing, lubrication, and protection without fuss. You get a thick silicone paste that stays put, won’t cure, and works well with most plastics and rubbers. It performs in vacuum systems, O-rings, glass pistons, and electrical connectors, while also blocking moisture and dirt. Because it handles heat from -40 to 392°F, you can trust it in tough spots. The 8-ounce bottle gives you plenty for repairs, marine gear, and long service use.
- Form:Paste
- Silicone-based:Silicone
- Tube/Container:Bottle
- Vacuum Use:Vacuum systems
- Water Resistant:Waterproof
- Temperature Stability:-40°F to 392°F
- Additional Feature:Compatible with plastics
- Additional Feature:Lowers elastomer permeation
- Additional Feature:Food/drinking-water certified
Molykote High-Vacuum Grease 5.3 oz (2-Pack)
Value Pack
Check Latest PriceThis Molykote High-Vacuum Grease 5.3 oz 2-pack is a smart pick for anyone who needs a reliable moly grease with strong heat resistance and a handy twin pack. You get 10.6 ounces total, so you can keep one tube ready for backup or split use between projects. Because it’s built for automotive work, you can trust it in high-vacuum jobs that need a tight seal. Its 300 degrees Celsius flash point adds peace of mind as heat rises. The compact 0.79 pound box is easy to store, and the single customer rating keeps expectations simple.
- Form:Grease
- Silicone-based:Moly grease
- Tube/Container:Box
- Vacuum Use:High-vacuum
- Water Resistant:Not stated
- Temperature Stability:300°C flash point
- Additional Feature:Two-pack value
- Additional Feature:Automotive moly grease
- Additional Feature:Flash point 300°C
Factors to Consider When Choosing Vacuum Grease
As I choose vacuum grease, I look first at how well it matches the vacuum system, because the wrong grease can break performance fast. I also check the temperature range, water resistance, chemical resistance, and dielectric protection, since each one helps the grease stay steady and reliable in real use. If you want fewer leaks and less frustration, I’d treat these factors like a checklist before you buy.
Vacuum Compatibility
Although vacuum grease may seem like a small detail, it can make or break the seal in a vacuum system. I look initially at vacuum compatibility because I want the grease to stay put and not ruin the chamber. Low volatility and low vapor pressure matter most, since they help keep the evacuated space clean. I also check that the grease holds seals tight at low pressure and cuts leak rates at joints and flanges. For mixed parts, I choose one that plays nicely with rubbers, O-rings, plastics, and glass-to-glass joints. I also prefer a formula that resists oxidation, chemical attack, and outgassing during long runs. That way, I protect both performance and peace of mind.
Temperature Range
I always check the temperature range initially, because a vacuum grease can look perfect on paper and still fail the moment heat or cold gets involved. I want its rating to cover my lowest and highest expected temperatures, whether that means -40°F in a cold shop or 200°C near hot equipment. A wider range gives me more confidence because the grease stays steady instead of hardening or softening at the wrong time. Whenever I expect real heat, I look for products rated 200°C to 204°C or higher. In cold spaces, I make sure the formula still works below zero. That stability protects sealing and lubrication, and it helps me avoid breakdowns, leaks, and messy surprises.
Water Resistance
Water resistance is the next thing I check, because a vacuum grease that handles heat well can still fail fast in a wet or humid spot. I want a grease that keeps sealing after long contact with water, so it won’t wash away and leave gaps. That steady barrier helps protect vacuum joints, O-rings, seals, and plug valves from rust and grime. I also look for products labeled waterproof, because that usually points to better durability in damp rooms. Whenever I’m working with electrical gear or lab glass, this matters even more, since moisture can hurt insulation and cause leaks at connectors. A grease that stays stable from cold to hot conditions gives me extra confidence whenever the weather, or the lab sink, gets messy.
Chemical Resistance
Chemical resistance matters just as much as water resistance, because a vacuum grease can look fine at first and still break down when it meets solvents, cleaning fluids, or other harsh chemicals. I always check that the formula can stay strong against both water and chemical exposure, since that keeps the seal from washing away or turning weak. Silicone-based greases often give me confidence because they stay stable and help protect rubber, plastic, and seal parts from chemical attack. I also look for low-volatility blends, because they don’t evaporate as fast during long use. If the grease may touch O-rings or gaskets, I make sure it’s labeled chemically resistant. In tougher jobs, I prefer products that hold up from about -40°F to 400°F, since heat and cold can speed up breakdown.
Dielectric Protection
Whenever you need vacuum grease for electrical work, dielectric protection should be one of the initial things you check. I look for strong insulation first, because it helps block voltage leaks and keeps moisture, dirt, and corrosion away from contacts. Next, I pay attention to temperature range. When a grease stays steady from about -40°F to 400°F, I can trust it when the heat rises or the cold bites back. I also prefer low volatility, since less evaporation means fewer gaps and less risk to delicate parts. Then I choose a non-curing, water-resistant formula so the barrier stays in place on terminals, connectors, O-rings, and seals. That steady shield gives me peace of mind, and it saves me from surprise sparks.
Material Compatibility
As I check material compatibility, I start with the exact elastomers, plastics, and seals in your system, because the right vacuum grease should protect parts, not wear them down. I look for formulas that name O-rings, rubber, and most plastics as safe, since that saves you from softening, cracking, or swollen seals. Silicone-based grease often helps here, because it plays nicely with rubber gaskets, valves, glass, and many nonmetal parts. I also make sure it won’t attack synthetic rubber or plastic connectors, especially around ground glass joints. Should you need electrical insulation, I confirm the grease is dielectric and non-conductive. And should food, water, or chemicals be involved, I want clear FDA, NSF, or resistance claims, so your system stays steady and your peace of mind stays intact.
Application Specifics
Whenever I help you choose vacuum grease, I start with the exact job it has to do, because that choice changes everything. I match the grease to the task initially. For vacuum sealing, I want low volatility and low vapor pressure, so it won’t outgas and spoil the system. For O-rings, ground glass joints, or connectors, I check that it spreads cleanly and protects the right surface. Whenever rubber, plastics, or elastomers are involved, I verify compatibility so seals don’t swell or crack. I also look at the real temperature range, because a grease that works from minus 40°F to 400°F can save a lot of grief. Upon electrical parts are involved, I choose one with dielectric and moisture-barrier strength to keep dirt, corrosion, and leakage away.
Compliance Standards
After I’ve matched the grease to the job, I always check the standards behind it, because labels can sound friendly while the paperwork tells the real story. I want clear proof, not just promises. Should the grease could touch food or water, I look for NSF registration, NSF H1, or FDA 21 CFR 175.300 approval. For electrical work, I verify that it’s a dielectric or electrical-insulating grease, so connectors and terminals stay protected. Then I check vacuum-service claims, because lab and chemical systems need seals that hold under low pressure. I also read the temperature and chemical-resistance details closely, since good compliance should support the full range, from about -40°F to 400°F. Whenever in doubt, I trust explicit certification over “safe” marketing talk.
Frequently Asked Questions
Can Vacuum Grease Be Used on Rubber O-Rings?
Yes, vacuum grease works on many rubber O-rings, but check the material first. Some rubbers can swell or break down. Silicone, nitrile, and Viton O-rings usually benefit from a very thin coat that helps sealing and installation.
How Often Should Vacuum Grease Be Reapplied?
I’d reapply vacuum grease when it looks dry, shows contamination, or after several assemblies, like renewing a castle’s moat. For most uses, that means every few months, but I’d inspect seals regularly and sooner if exposed to heat.
Does Vacuum Grease Affect Electrical Conductivity?
Vacuum grease usually does not conduct electricity, and it can act as an insulator on contacts. If you need electrical conductivity, do not use it on terminals or grounded parts, since it can increase resistance and disrupt signals.
Is Vacuum Grease Safe for Plastic Components?
Vacuum grease is generally compatible with many plastics, but I would test it first because about 30% of plastic failures are caused by chemical incompatibility. I would avoid using unverified greases on polycarbonate, acrylic, and polystyrene.
How Do You Remove Old Vacuum Grease Residue?
I remove old vacuum grease with a lint free cloth, then I wipe the area with isopropyl alcohol or a mild solvent. I scrape stubborn buildup gently, and I dry everything completely before reapplying grease.
Conclusion
As I choose vacuum grease, I’m really choosing peace of mind for a seal that has to work like a tiny fortress. The right pick can hug glass, O-rings, and plastics so tightly it feels almost magical. Should you match the grease to your system, you’ll cut leaks, tame outgassing, and avoid messy failures. That means smoother work, fewer surprises, and a setup that stays sealed so well it could survive a dramatic thunderstorm in a shoebox.
