Black stainless braided PTFE hose in dash 10, supplied by the metre. This is the size used for oil cooler circuits, dry sump feed and return, and fuel supply on builds that outflow smaller lines. The PTFE liner shrugs off hot oil and modern fuel blends, and unlike rubber it will not deteriorate internally and shed material into the system. The braided cover, finished in black, protects against chafing and gives the hose its pressure capability. Bear in mind that dash 10 PTFE is genuinely stiff: plan the routing around wide sweeps, use angled ends where space is tight, and clamp the run so its weight is not carried by the fittings.