10 Best Fuel Injection Oil Supply Lines

Buying Guide

Choosing the best fuel injection oil supply lines for your project means balancing material chemistry, pressure ratings, sizing standards, and installation hardware. The wrong hose can weep fuel under pressure, collapse in a vacuum, or degrade after months of heat cycling. This guide breaks down the practical factors that separate a reliable line from one that will leave you stranded.

Sizing and Capacity

Fuel injection oil supply lines are sold using two main sizing conventions: inner diameter measured in fractions of an inch and AN (Army-Navy) dash numbers. Stock-style EFI systems often use 5/16-inch or 3/8-inch ID hose, which matches many factory fuel rails and dampers. Performance builds and turbo oil feeds frequently move to 6AN or 8AN hose because the fittings seal more positively under high pressure and the braided cover resists abrasion.

If you are plumbing an oil feed for a turbocharger or a remote oil cooler, measure the port threads on both ends before ordering. A 6AN line is roughly equivalent to 3/8-inch ID, while 16AN is closer to 1-inch ID and is generally reserved for high-flow oil cooler circuits or large fuel systems. Always buy slightly more length than your measured path; tight bends and engine movement consume more hose than a straight-line measurement suggests.

Material Tradeoffs: NBR, CPE, and PTFE

The rubber or polymer inside the hose determines what fluids it can carry and how long it will last. Nitrile butadiene rubber (NBR) is the most common material for push-lock fuel and oil hoses. It is affordable, flexible, and rated for gasoline and diesel. However, standard NBR can swell over time when exposed to high concentrations of ethanol or modern synthetic oils. If your build runs E85 or methanol, look for hoses with a PTFE (Teflon) liner. PTFE does not absorb fuel, resists virtually all automotive chemicals, and handles higher temperatures than rubber alone.

Chlorinated polyethylene (CPE) is another option found in braided hose kits. It offers better heat and ozone resistance than basic NBR and is often paired with a stainless or nylon braid for added strength. The tradeoff is stiffness: PTFE and braided CPE hoses are harder to route in tight engine bays than soft push-lock rubber. For a stock-replacement fuel injection oil supply line, NBR push-lock is usually sufficient. For a race or turbo application, PTFE or CPE is the safer long-term choice.

Pressure Ratings and Safety Margins

Most quality fuel injection oil supply lines are rated to at least 300 PSI working pressure. That is well above the operating pressure of a typical port-fuel injection system, which usually runs between 40 and 60 PSI. Direct-injection and high-performance EFI systems can exceed 100 PSI, and turbo oil feeds see pressure spikes from the engine’s oiling system. A 300 PSI rating provides a comfortable safety margin, but never assume a universal number applies to your specific hose. Verify the printed rating on the product, and remember that temperature reduces a hose’s effective pressure capacity. If you are running a high-pressure mechanical fuel pump or a ball-bearing turbo with a restrictor, confirm that the entire line assembly—including fittings—is rated for the peak pressure your system will see.

Installation and Fitting Compatibility

Push-lock hose is the easiest to install: you simply push it onto a barbed fitting and add a hose clamp. It is ideal for quick repairs and stock-style routing. AN hose, on the other hand, requires cutting the hose squarely, installing the socket and nipple fittings, and tightening them with wrenches. The advantage is a more secure, reusable connection that will not blow off under pressure.

When you shop for fuel injection oil supply lines, pay attention to what is included. Some kits ship as bulk hose only, while others include a full set of straight, 45-degree, and 90-degree fittings. If you are converting from stock hard lines to braided hose, a kit with adapters saves multiple trips to the parts store. Also consider the bend radius of the hose. Braided stainless lines have a larger minimum bend radius than rubber, so a 90-degree fitting is often necessary to clear valve covers or frame rails without kinking the line.

Maintenance and Reliability Signals

Inspect your fuel injection oil supply lines at every oil change or seasonal service. Look for surface cracking, hardening, or bulging near fittings. Ethanol fuels accelerate rubber degradation, so PTFE-lined hoses generally last longer in modern pump-gas environments. If you notice a fuel smell in the garage, trace every connection; push-lock hoses can weep if the clamp loosens, while AN fittings may leak if they were not torqued properly during assembly.

Reliability also depends on keeping the hose away from exhaust components and sharp edges. Even a braided stainless line can fail if it rubs against a metal bracket. Use Adel clamps or padded separators to prevent chafing, and always allow a small service loop so the engine can rock on its mounts without pulling the fittings tight.

How to Compare Reviews

When reading feedback on fuel injection oil supply lines, prioritize comments that mention specific vehicles or builds similar to yours. A five-star review from a lawn-mower owner is less relevant than a detailed install note from someone running the same turbo or EFI system you have. Look for patterns: if multiple buyers mention the hose being too stiff to route, or fittings leaking at the crimp, treat that as a red flag regardless of the average star rating.

Pay special attention to reviews that include photos of the installed line. They reveal hose-routing clearances, fitting quality, and whether the included hardware matches the description. For application-specific kits, such as Harley-Davidson fuel injection lines or Cummins oil feed tubes, verify that the reviewer lists the exact year and model. Fitment issues are the most common reason for negative feedback on direct-replacement lines.

Final Recommendation

If you need a dependable, easy-to-install fuel injection oil supply line for a daily driver or mild performance build, the 3/8-inch and 5/16-inch NBR push-lock hoses at the top of our list offer the best combination of verified durability and pressure capacity. They are SAE-rated, widely trusted, and simple to cut to length.

For ethanol blends, forced induction, or dedicated race cars, move to a PTFE-lined braided kit. The EFI-specific 6AN PTFE options in our rankings include the fittings and adapters needed for modern fuel injection systems, and they resist the fuel permeation that ruins standard rubber over time.

Builders with large oil coolers or high-flow fuel systems should consider the 16AN braided kit, while those restoring a Harley-Davidson touring bike or working with a specific OEM injection pump should choose the direct-fit options ranked lower in the list. Match the hose material to your fluid chemistry, confirm your fitting sizes before ordering, and always buy a little extra length to accommodate the realities of under-hood routing.