Best Gasket Sealers: Keep Fluids Inside Where They Belong

These top gasket sealers are helpful in automotive work

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Gasket sealer is used when you need to seal something but it doesn’t have a gasket. Most car and truck manufacturers argue against the use of gasket sealer, largely because people often use way too much. But there are times when gasket sealer is specified by the manufacturer (for items such as differential covers and oil pans, for example). Here are the best gasket sealers on the market. 

  • Best Overall
    Gasgacinch 440-A
    Summary
    Summary
    Gasgacinch is one of the go-to gasket sealers for engine builders and technicians. It applies with a high tack to adhere to any surface.
    Pros
    Pros
    The brush-on application ensures that you can’t put too much of this stuff on. It works in all conditions in automotive applications. It also works well as a belt dressing. Maintains flexibility when cured.
    Cons
    Cons
    This product is really hard to clean off your hands without harsh chemicals.  Some buyers claim it isn’t as high quality as it used to be.
  • Best Value
    Permatex Ultra Black
    Summary
    Summary
    Great for use on differential housing covers, oil pans, valve covers, and any surfaces exposed to oil.
    Pros
    Pros
    This is the best gasket sealer to use when the manufacturer calls for a liquid gasket vice paper, cork, or paper.  Retains sealing qualities between -65 and 500 degrees Fahrenheit.
    Cons
    Cons
    It is easy to use too much of this product. The excess product ends up where you don’t want it: on the inside of moving parts. It’s also hard to clean up.
  • Honorable Mention
    Permatex Aviation Form-A-Gasket
    Summary
    Summary
    This is another go-to sealant for professionals. It dries slowly to give you time to assemble your parts, and it adheres to most surfaces.
    Pros
    Pros
    It’s great when used to adhere to a gasket (paper, rubber, or cork) to a horizontal or vertical surface for mounting. It’s resistant to gas, oil, and most acids. Maintains flexibility when cured, even down to -65 degrees and up to 400 degrees Fahrenheit.
    Cons
    Cons
    Fumes are really strong, so this product must be used in a ventilated space. Not terribly good for threads on fuel lines. Bottles tend to leak over time with normal use.

Tips

  • Rarely do auto manufacturers recommend using a silicone- or latex-based liquid sealant by itself. Those that do insist that only a small amount be used.
  • When using a squeeze-tube type of gasket sealer, only use what you need. Don’t glob it on and wipe off the excess. Otherwise, you’ll be picking chunks of it out of your oil.
  • Liquid brush-on gasket adhesives are recommended by manufacturers for transmission oil pans since latex or silicone sealers can break off and clog vital orifices, damaging your transmission.
  • When using a gasket sealer on exhaust components, pick one with a high copper content to resist the high temperatures in exhaust systems.
  • Whether you use a gasket sealer or not, remove as much of the old gasket as possible without scraping or scratching the mating surfaces. If you don’t get all the old material off, especially out of grooves, or if you scratch the surface, you will cause leaks instead of sealing them.

FAQs

Q: What is the difference between a gasket adhesive and a gasket sealer?

A: A gasket sealer is the gooey, gloppy stuff every one associates with gasket sealing. Gasket adhesive is more of an extra-strength contact cement with properties that make it chemically resistant.

Q: Why use gasket adhesive or sealer when my part comes with a gasket?

A: Good question. Except in certain circumstances, a gasket sealer is used as nothing more than an adhesive. It’s there to keep the gasket from slipping during installation.

Q: My new oil pan didn’t come with a gasket. What should I use to seal it?

A: When using in place of an actual gasket, run a small bead of silicone or latex gasket sealer around the edge of the pan outside the bolt holes. Your bead should not be larger than 1/8 inch in width/diameter. Excess gasket sealer can actually cause leakage.

Final Thoughts

Our choice for the best overall gasket sealer, Gasgacinch 440-A, is the choice of professional race engine builders.

Our pick for the best value gasket sealer, Permatex Ultra Black, is a great choice for those times when you don’t have a paper, cork, or rubber gasket and you’re putting parts together that will be subjected to a lot of oil when in use.