Pick the wrong gasket material for a diesel fuel system and it swells, softens, and leaks. The right one resists diesel, biodiesel, and additives while handling the temperatures it’ll see. Here are the best gasket materials for diesel fuel, and which to avoid.
Best overall: FKM (Viton)
FKM, best known by the brand name Viton, is the top choice for demanding diesel applications. It offers outstanding resistance to diesel, biodiesel, ethanol blends, oils, and aggressive additives, and stays flexible up to around 400 F. If your system runs hot or uses a high percentage of fuel additives, Viton is the safe pick.
Best value: NBR (Nitrile)
Nitrile (NBR) is the most widely used material in automotive fuel-system gaskets thanks to excellent resistance to diesel, petrol, and mineral oils at a much lower cost than Viton. Its temperature range is more limited (roughly -30 to 200 F), but for standard diesel sealing it’s hard to beat on price.
Most chemically inert: PTFE (Teflon)
PTFE is essentially inert to diesel and other aggressive fuels and additives, with exceptional thermal and chemical resistance. It’s ideal for the harshest fuels, though it’s less compressible than rubber, so it suits flat-faced, well-machined sealing surfaces.
Materials to avoid with diesel
- EPDM — great for water and brake fluid, but it swells badly in petroleum fuels. Never use it with diesel.
- Neoprene and SBR — only fair-to-poor fuel resistance; they degrade over time in diesel.
How to choose
- Standard diesel, budget-conscious: use Nitrile (NBR).
- Biodiesel, additives, or high heat: step up to FKM (Viton).
- Most aggressive fuels / flat surfaces: use PTFE.
- Always confirm the temperature range and fuel/additive blend your application sees before finalizing.