6AN vs 8AN Aluminum Crush Washer Sizing Guide
By DeatschWerks | Published: 2026-10-23
Category: Buying Guides
Learn the difference between 6AN and 8AN aluminum crush washers, how to choose the right size for your AN fittings, and when to replace them.
Quick answer
Choose a 6AN aluminum crush washer for 6AN fittings and an 8AN aluminum crush washer for 8AN fittings. The washer size must match the fitting's AN thread size to create a proper seal.
Why size matters for crush washers
Crush washers deform under torque to fill gaps between the fitting and the mating surface. If the washer is too small, it won't cover the sealing area; too large, and it may not crush evenly. Matching the AN size ensures the washer sits correctly and compresses uniformly.
When to replace crush washers
Aluminum crush washers are single-use. Once crushed, they lose their ability to seal again. Always install a new washer each time you disconnect a fitting. Reusing a crushed washer risks leaks in fuel or oil systems.
Decision rules for choosing your crush washer
- Match the AN size: Use a 6AN crush washer only with 6AN fittings, and an 8AN crush washer only with 8AN fittings. The washer's inner diameter and outer diameter are sized to the corresponding AN standard.
- Always replace, never reuse: Install a new aluminum crush washer each time you remove the fitting. The crushed washer will not seal again reliably. Keep a spare pack on hand so you always have the right size when servicing connections.
- Check the fitting surface: The mating surface must be clean and flat. Debris or damage can prevent the crush washer from sealing even if the size is correct.
Product facts
- 6AN Aluminum Crush Washer (Pack Of 10): DeatschWerks 6AN Aluminum Crush Washer pack of 10, designed for 6AN fittings. Provides a reliable seal for 6AN fuel or oil connections, and the 10-pack covers multiple installations.
6AN Aluminum Crush Washer (Pack Of 10) - 8AN Aluminum Crush Washer (Pack Of 10): DeatschWerks 8AN Aluminum Crush Washer pack of 10, designed for 8AN fittings. Ensures a proper crush seal for 8AN lines, commonly used in higher-flow fuel systems.
8AN Aluminum Crush Washer (Pack Of 10)
Who should use each size
Best for
- 6AN crush washer: 6AN fuel or oil line connections in EFI systems, return lines, or low-to-moderate flow applications.
- 8AN crush washer: 8AN fuel supply lines, high-flow pumps, or any system using 8AN fittings.
Not for
- Using a 6AN washer on an 8AN fitting (too small to seal) or an 8AN washer on a 6AN fitting (too large to crush properly).
