Gaskets & Seals

The best engine gaskets and seals for a build are the ones matched to your engine, bore size, and gasket thickness, from a maker that specializes in sealing. For most performance builds in this collection that means a Cometic multi-layer steel (MLS) head gasket in the correct bore and thickness, with JE Pro Seal, Tomei, and genuine Subaru OEM kits covering other engines and full refresh jobs. Always confirm your engine and bore before ordering, because a head gasket is not interchangeable between engines.

Gaskets and seals keep combustion pressure, oil, and coolant where they belong. The head gasket is the critical one: it seals the cylinder head to the block and sees the highest pressure, which is why bore diameter and thickness are listed so precisely in this collection. Around it sit valve cover gaskets, crankshaft seals, thermostat gaskets, and full engine gasket kits that bundle everything needed for a teardown or rebuild. For a focused shortlist, see the dedicated head gaskets collection.

Cometic dominates this collection by a wide margin, and its listings show why builders shop by specification: MLS head gaskets are listed by exact bore and thickness, such as 81.5mm and .040 inch for Honda B-series VTEC applications and 87mm and .036 inch for the Cometic Honda K20/K24 head gasket. Cometic is a gasket specialist whose range extends across many engines. Picking the right part is a measuring exercise, not a guessing one.

JE Pistons contributes its Pro Seal head gaskets, including SR20DET applications listed by bore and thickness for both rear-wheel-drive and front-wheel-drive layouts. JE is known first for forged pistons, and Pro Seal extends that focus to the sealing side of a build.

Tomei offers metal head gaskets for Nissan SR20 and Subaru turbo engines, including the Tomei 1.2mm head gasket for 2004-2020 STI and 2006-2014 WRX models, sold as a pair for the flat-four. Tomei is a Japanese tuning house with a strong engine-parts reputation. Subaru owners should note the pair format when comparing prices.

Subaru OEM covers the factory route: full engine gasket and seal kits for WRX, STI, and Forester XT applications, plus individual valve cover gaskets and washers. Genuine kits suit refresh and repair work where factory fit is the priority. For background on why head gaskets fail, read what causes a blown head gasket in a Subaru.

How do I choose head gasket bore and thickness?

Match the bore to your engine's actual bore size, including any overbore from machining, and choose thickness based on your build goals. Measure first and check your year and model before ordering.

Should I replace all gaskets during a rebuild?

It is good practice. Full engine gasket and seal kits exist for exactly this reason: once the engine is apart, reusing old seals risks leaks that cost far more labor to fix later.

Are MLS head gaskets reusable?

No. Head gaskets are single-use sealing parts and should be replaced whenever the head is removed, regardless of type. Always follow the manufacturer's torque sequence and specifications on installation.

Do gaskets differ between WRX and STI engines?

Yes. Even within Subaru's turbo range, applications are split by year and engine, which is why listings name exact ranges. Check your year and model against the product title before buying.