The right choice for Automotive seals

High engine temperatures, extended warranties and the drive to reduce emissions all demand high-quality rubber sealing products. With excellent resistance to high temperatures and tolerance of stressful conditions, rubber is the perfect material for sealing and protecting in the automotive environment.

A wide variety of sealing solutions are used throughout today’s vehicles. These include O-Rings that withstand high pressures in shock absorbers, sophisticated gaskets in electronic control units (ECUs), safety critical custom-moulded components in braking systems and seals that withstand extreme temperatures, pressures and aggressive media in fuel injectors.

There are a range of compounds offering tremendous advantages for automotive companies seeking to meet stringent industry requirements while providing opportunities for competitive advantage. Suitable materials include; Viton® / FKM, AEM, HNBR, PTFE and FFKM.

Viton® (FKM)

Viton® is an all-round material capable of handling a diverse array of applications, particularly sealing jobs involving movement. It offers excellent resistance to fuels, oils and fluids. Combined with its exceptional heat resistance, Viton® O-rings are extremely versatile and continue to be the material of choice for demanding fuel system and powertrain applications.


AEM (Vamac®) has been successfully used in automotive hose applications. This material provides a cost effective approach to a wide range of challenging underhood applications, including power steering, engine and transmission oil cooler hoses, ignition cable, spark plug boots or primary wiring.

HNBR (Hydrogenated Nitrile)

The automotive market is the largest consumer of HNBR. This material is used for many dynamic and static seals, hoses and belts. HNBR offers excellent resistance to most common automotive fluids including engine oil, coolant and fuel. Its unique properties and higher temperature rating make HNBR ideal for performance-demanding applications.


FFKM (perfluoroelastomers) compounds are designed for demanding sealing applications that are subject to aggressive chemical and high heat environments. FFKM compounds combine the positive properties of PTFE with the elastic behaviour of Viton® / FKM. They provide outstanding resistance to a wide range of fluids and chemicals including automotive lubricants, fuels, and additives. Typical end use products include O-rings, seals, gaskets, and complex moulded parts. In general, FFKM compounds are only used if other materials cannot meet the very high application specifications.


Even with today’s broad selection of specialty elastomers, Neoprene remains the choice for many underhood and underbody parts that require a reasonably priced, mid-performance polymer with a good all-around balance of performance properties.

FEP PTFE Encapsulated O-rings

FEP encapsulated O-rings comprise of a Viton® or Silicone elastomer core which has been seamlessly encapsulated in a jacket of PTFE (Teflon®) fluoropolymer. These O-rings handle surface wear well, offering outstanding corrosion and abrasion resistance, non-permeability, chemical inertness and low absorption. They can also operate within a wide temperature variance of between -60℃ to +200℃ (silicone FEPs) and -20℃ to +200℃ (Viton® FEPs).

It is important to note that pure PTFE O-rings are very rigid and hard to apply, which makes them more suited to static applications. PTFE O-rings are often used in automotive steering devices and paint guns.

Consumers’ unique requirements often cannot be satisfied by standard sealing materials. Aesthetic and functional needs, along with regulatory restraints, demand more adaptable solutions. The manufacture of rubber parts, unlike that of plastic components, requires extensive experience to achieve the right result. Knowledge and experience of how a material behaves when processed is critical for any automotive application.

Modern high-performance engines require sealing solutions that deliver top performance in terms of operating reliability and service life. Engine seals ensure that there is no leakage of fluids, coolant, oil and air from either external or internal passages of the internal combustion engine. The cylinders are tightly sealed to allow maximum compression within the engine cylinder.

A range of materials offer the capability to provide resistance to fuel and high temperatures. These materials include Viton® / FKM, HNBR and FFKM elastomers. These materials are suitable for fuel injection seals, fuel pump seals, manifold gaskets and diaphragms.

Transmission fluid seals are primarily designed to stop fluid leakage in order to maintain the required pressure inside an engine. Automotive transmission seal material usage varies by manufacturer and, in some cases, by seal type within a transmission. AEM (Vamac®) is the most common elastomer, although various fluorocarbon (Viton® / FKM) elastomers are also used. Both materials have their advantages and disadvantages. AEM degrades faster than Viton®. Standard fluorocarbons offer good fluid resistance, but low temperature flexibility is poor. Specialist Viton® / FKM grades must therefore be selected, but they come at a price.

Hostile engine environments and tight emission regulations require the best quality rubber. Eastern Seals can offer a range of seals and gaskets which deliver high levels of performance. From a general purpose elastomer such as standard Nitrile, through to special grades of HNBR, Viton® and FFKM, our range of materials can support a wide variety of automotive applications.

Automotive seals can be supplied with Level 3 PPAP documentation, along with CPK and PPK controls.

For more information on our range of Automotive sealing products, download our latest Automotive Sealing Solutions brochure. To discuss your application needs further, please call our Technical sales team on +44 (0) 1670 840529 or email