Braided oil lines are what you reach for the moment a build outgrows factory plumbing: an external oil cooler, a transmission cooler, a catch can, or a turbo feed. They look great, they resist abrasion, and they can carry hot oil at pressure for years. They can also leak all over your garage if you pick the wrong size, the wrong liner, or route them next to a downpipe. This guide covers AN sizing, PTFE vs rubber, routing rules, and how to plumb an external cooler on the Audi 3.0T starting with our EA837 oil cooler adapter plate.
What Braided Oil Lines Actually Are
A braided line is two layers: an inner hose that carries the fluid and an outer braid (usually stainless steel, sometimes nylon) that protects it from abrasion and adds burst strength. The inner layer is where the real choice happens. The braid is armor, not the seal.
The ends are AN fittings, a flare-based system originally developed for military aircraft. Each hose end threads onto a mating male AN fitting, and the 37-degree flare does the sealing, no thread sealant needed.
AN Sizes Explained
The "dash" size is the outside diameter of the equivalent hard tube in sixteenths of an inch. Hose inner diameter varies slightly by brand and liner, so compare published ID if flow is critical.
| AN size | Tube OD | Typical uses |
|---|---|---|
| -6AN | 3/8 in | Turbo oil feeds, fuel lines, many transmission cooler lines |
| -8AN | 1/2 in | Engine oil cooler lines on smaller engines, larger transmission coolers, fuel feeds |
| -10AN | 5/8 in | Engine oil cooler lines on larger engines, crankcase breather and catch can lines |
| -12AN | 3/4 in | Turbo oil drains, high-flow breathers |
For an engine oil cooler on a V6 like the EA837, -8 or -10 is the usual range. Bigger lowers restriction but adds weight, cost and routing headaches. Transmission coolers commonly run -6 or -8. Match the line to your cooler's ports and your adapter, not to what looks coolest.
PTFE vs Rubber Braided Oil Lines
This is the question most buyers get wrong. Both work for oil. They are not interchangeable at the hose ends.
| Rubber-core braided | PTFE-lined braided | |
|---|---|---|
| Flexibility | Very flexible, tight bends | Stiffer, needs a larger bend radius |
| Heat tolerance | Good for engine oil | Higher |
| Chemical resistance | Good for oil and coolant | Excellent, including fuel and E85 |
| Permeation | Can seep fuel vapor over time | Very low |
| Hose ends | Standard reusable AN ends | PTFE-specific ends with an olive or ferrule |
| Best for | Oil cooler and breather lines on a budget | Fuel systems, very hot routing, long-term builds |
The mistake that ruins weekends: using a rubber-hose end on PTFE hose. It will seem tight and then weep. Buy ends made for your hose type.
Buyer's Checklist for Braided Oil Lines
- ✅ Correct AN size for the cooler, adapter and flow you need.
- ✅ Liner that matches the fluid and heat: rubber for most oil jobs, PTFE for fuel and very hot routes.
- ✅ Hose ends designed for that exact hose type and brand family.
- ✅ Adapters for the ports you actually have: ORB, NPT or metric. Tapered NPT needs thread sealant (paste, not tape that can shred into oil); ORB seals with an O-ring.
- ✅ Fire sleeve or heat shielding for any run near the exhaust.
- ✅ Clamps or P-clips to support long runs.
Plumbing an Oil Cooler on the Audi 3.0T
From the factory, the EA837 shares one water-to-oil heat exchanger between the oil and coolant, so a hot cooling system heats the oil and vice versa. On track, both climb together. The Vorsprung Oil Cooler Adapter Plate ($84.99) bolts in place of that exchanger (OEM 06E117021G) and routes oil to an external cooler instead. It is CNC-machined billet aluminum, anodized, with ports sized for standard ORB fittings.
- ✅ Plate: replaces the factory exchanger, fittings and cooler not included.
- ✅ Fittings: ORB-to-AN adapters in your chosen size, typically -8 or -10.
- ✅ Lines: braided oil lines cut to length with matching hose ends.
- ✅ Cooler: sized so the oil still reaches operating temperature on cold days. A thermostatic control is worth considering if you drive year-round.
We sell the plate by itself so you can pick the cooler, fittings and hose that fit your car and budget, instead of paying for a bundle built around someone else's choices.
Shop the EA837 Oil Cooler Adapter Plate, $84.99
✅ CNC-machined billet adapters ✅ Plumbing help from real 3.0T owners ✅ Fast US shipping
Transmission Cooler Adapters
Automatics and dual-clutch boxes hate heat as much as engines do. Our DSG transmission oil cooler adapter ($49.99) replaces OEM 0B5325060C on the DL501 7-speed S tronic in B8/B8.5 A4, A5, S5 and RS5, giving you a threaded port for an external cooler. The ZF8HP55 transmission oil cooler adapter ($59.99) does the same for the 8-speed automatic in the C7 A6 and A7 and D4 A8. Both are adapter-only, so plan your braided oil lines and fittings alongside them.
AN Fittings We Stock
We carry a wide range of Vibrant aluminum AN fittings. A few that come up constantly on these builds:
- ✅ Vibrant -10AN to -10AN union ($27.95), handy with our billet PCV breather quick connect, 19mm to 10AN ($44.99-$49.99) for catch can routing.
- ✅ Vibrant -8AN to -8AN union ($26.95) for joining or extending -8 oil cooler lines.
- ✅ Vibrant -6AN to -6AN union ($24.95) for transmission cooler and feed lines.
- ✅ Vibrant -8AN to 1/2in NPT adapter ($25.95) for coolers and sandwich plates with NPT ports.
Braided hose itself is sourced separately right now. Tell us your cooler and we will help you size the rest.
Routing and Install Rules
- ✅ Keep lines well clear of the exhaust and turbos, and use fire sleeve where you cannot.
- ✅ Respect the minimum bend radius. Kinked hose restricts flow and fails early.
- ✅ Leave slack for engine movement on its mounts, especially between the engine and a chassis-mounted cooler.
- ✅ Support long runs every foot or so with cushioned clamps.
- ✅ Cut braided hose cleanly with a cut-off wheel and tape, then blow out debris before assembly.
- ✅ Lubricate fitting threads lightly with oil, torque snug, and leak check at operating temperature.
- ✅ Replace the factory seals you disturb. The TruSeal oil gasket upgrade covers the oil filter housing seals, and our oil filter housing gasket guide and step-by-step replacement guide cover that job.
Building a crankcase breather or catch can too? Start with our PCV breather hose guide and the billet PCV housing adapter. For the charge-air side of cooling, see the GP Ice heat exchanger and our cooling solutions collection.
Braided Oil Lines FAQ
What size braided oil lines do I need for an oil cooler?
Most engine oil cooler setups on a V6 like the Audi 3.0T use -8AN or -10AN lines. Match the size to your cooler ports and adapter fittings.
Are PTFE or rubber braided oil lines better?
Rubber-core lines are more flexible and cheaper and work well for oil. PTFE-lined lines handle more heat and chemicals and barely permeate, so they are the pick for fuel and very hot routing. Each needs its own hose ends.
What does AN size mean?
The dash number is the outside diameter of the matching hard tube in sixteenths of an inch. For example, -8AN equals 1/2 inch and -10AN equals 5/8 inch.
Do AN fittings need thread sealant?
No. AN fittings seal on the 37-degree flare. Only tapered NPT threads need sealant, and a paste is better than tape near oil passages. ORB ports seal with an O-ring.
How do I add an external oil cooler to an Audi 3.0T?
Replace the factory water-to-oil heat exchanger with the EA837 oil cooler adapter plate, add ORB-to-AN fittings, run braided oil lines to an external cooler, and leak check at temperature.
Can braided oil lines be routed near the exhaust?
Only with protection. Keep as much distance as possible, add fire sleeve or heat shielding, and support the line so it cannot move into hot parts.
How often should braided oil lines be replaced?
There is no fixed interval. Inspect them at every oil change for weeping at the ends, frayed braid or stiff, heat-damaged sections and replace at the first sign of trouble.
Bottom Line on Braided Oil Lines
Good braided oil lines come down to three choices: the right AN size, the right liner, and hose ends that match. Route them away from heat, give them slack, and leak check hot. On the Audi 3.0T, start with the Vorsprung EA837 oil cooler adapter plate to give your oil its own cooling loop, then add the fittings and lines that suit your cooler.
Shop the EA837 Oil Cooler Adapter Plate, $84.99
Drive the difference. Drive Vorsprung.
Prices checked September 25, 2026 and subject to change.
