6an Male to 18mm x1.5 O-Ring Fitting - Blue

The 6AN Male to 18mm x1.5 O-Ring Fitting in Blue is a precision adapter engineered for high-performance fuel systems, hydraulic lines, and custom cooling applications in modified vehicles. Whether you're building a fuel-injected engine swap, upgrading your cooling circuit, or integrating aftermarket components, this REDHORSE PERFORMANCE fitting bridges the critical gap between AN-spec hose fittings and metric ports. It's the kind of adapter that experienced mechanics and fabricators rely on when OEM solutions fall short or when mixing metric and imperial plumbing standards.

This fitting combines a 6AN male thread (common on fuel rails, pressure regulators, and aftermarket manifolds) with an 18mm x 1.5 O-ring port, the standard metric connection point found on many OEM fuel pumps, thermostats, and European-derived engine blocks. The O-ring seal design eliminates the need for PTFE tape, creating a more robust, vibration-resistant connection that handles the thermal cycling and pressure spikes of forced-induction and high-RPM applications. The anodized blue finish provides both visual identification and corrosion resistance, while the compact machined body ensures clearance in tight engine bays and transmission tunnels where custom plumbing routes demand precision fit.

This adapter is ideal for mechanics fabricating custom fuel systems in LS, Honda K-series, and turbo conversions where metric and AN components intersect. It's equally essential for cooling system modifications, especially when retrofitting aftermarket thermostats or integrating remote oil coolers into vehicles with metric ports. Installation is straightforward—thread the AN side into your fuel rail or hose fitting, and seat the O-ring end onto the metric port with hand-tight plus one-quarter turn; over-torque will damage the seal. Verify compatibility with your specific pump, regulator, or block before ordering to ensure the 18mm x 1.5 port matches your application.