2010-2018 Audi A8 Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2010-2018 Audi A8 uses DOT 4 brake fluid. Audi's own service literature for the A8 calls for new FMVSS 116 DOT 4 (or SAE J1703) fluid under Audi part number B 000 750, and Audi's US maintenance schedules call for a complete brake fluid change every 2 years regardless of mileage. The system holds roughly 1 liter, so a full flush is a small, inexpensive job that protects some very expensive hardware.

What Brake Fluid the Audi A8 Takes

Audi of America's service information sheet for the 2011 A8 lists the brake system fluid specification plainly: use new fluid only, FMVSS 116 DOT 4 or SAE J1703, with the genuine fluid sold under part number B 000 750. The same sheet puts the brake system capacity at approximately 1.0 L (1.1 qt). That capacity is the whole system, not what you will buy for a flush; plan on extra fluid to push the old fluid out of all four calipers and to leave the reservoir full.

Audi's owner's manuals add the reasons behind the rule. The fluid must be fresh and unused, it gradually absorbs moisture from the air, and if the water content climbs too high it can corrode the brake system over time. The manual also warns that fluid left in the system too long can cause vapor lock under heavy braking, which is the scenario that matters on a heavy, powerful sedan like the A8.

DOT 4 vs DOT 3 vs Low-Viscosity DOT 4

The federal standard, FMVSS 116, sets the minimums every bottle has to meet. For DOT 4, the dry equilibrium reflux boiling point must be at least 230 C (446 F) and the wet boiling point (after the fluid has absorbed a set amount of water) at least 155 C (311 F). DOT 3 only has to reach 205 C (401 F) dry and 140 C (284 F) wet. That gap is why you should not top off an A8 with DOT 3 from the corner store: it lowers the boiling point of the whole system.

The standard also caps cold viscosity. DOT 4 may be no thicker than 1,800 mm2/s at minus 40, while DOT 3 is capped at 1,500. Low-viscosity DOT 4 fluids go much further. Pentosin DOT 4 LV, for example, lists a kinematic viscosity of 700 mm2/s or less at minus 40 C, a dry boiling point of at least 265 C (509 F) and a wet boiling point of at least 170 C (338 F). Its data sheet cross-references it to the Audi/Volkswagen B 000 750 fluid part numbers and states it can be used in any vehicle that requires DOT 4. Thin fluid moves through ABS and stability-control valves faster in the cold, and Pentosin describes it as ideal for modern vehicles with ESP and ABS.

Never put DOT 5 silicone fluid in an A8. It is a different chemistry from the glycol-based DOT 4 the car was designed around, and the two should not be mixed.

How Often to Flush It, and Why Mileage Does Not Matter

Audi's US maintenance schedules for this era, including the model year 2016 schedule that covers the A8, list replacing the brake fluid on all vehicles every 2 years regardless of mileage. The 2019 all-models schedule repeats the same line. The interval is time-based because the enemy is moisture, not wear. Brake fluid is hygroscopic: it pulls water vapor through hoses, seals and the reservoir vent whether the car is driven daily or sits in a garage. A low-mileage A8 that is five years old can have worse fluid than a high-mileage one that was flushed last year.

Water in the fluid does two kinds of damage. It drops the boiling point toward the wet rating, so a long downhill or a hard stop from highway speed can boil fluid in the calipers and give you a pedal that sinks. And it corrodes the internals of the calipers, the ABS hydraulic unit and the master cylinder, which are far more expensive to replace than a bottle of fluid. If you drive hard, tow, or live in a humid climate, flushing more often than every 2 years is reasonable; Audi's schedule is a maximum, not a target.

Signs the Fluid Is Overdue

• Soft or sinking pedal after repeated hard stops - the classic sign of fluid boiling in the calipers. It usually firms up once the brakes cool, which is exactly why it gets ignored.
• Dark, cloudy fluid in the reservoir - fresh DOT 4 is typically amber and clear. Color is only a rough guide, so do not rely on it alone.
• No record of a flush in the last 2 years - on a car this age, assume it is due unless the service history proves otherwise.
• Fluid level dropping - the level falls slowly as pads wear, but a noticeable drop between checks means a leak at a hose, line or caliper and needs attention before a flush.
• Brake warning light - low fluid can trigger it. Diagnose the cause; do not just top off.

A shop can test the fluid with a boiling-point tester or moisture test strips. That is useful information, but on this car the calendar is the real rule.

How the Flush Is Done on an A8

The job itself is simple: open the reservoir, then bleed each caliper in turn until clean fluid with no air comes out, keeping the reservoir from ever running low so air cannot enter the master cylinder or the ABS unit. Most shops use a pressure bleeder at the reservoir; the two-person pedal method also works. Follow the bleed sequence in the factory repair information for your car, and put the bleeder caps back afterward, because Audi's schedule specifically checks that they are fitted.

Two cautions from the owner's manual are worth repeating. Brake fluid is poisonous, and it attacks paint on contact, so cover the fender and clean up any spill right away. And only use fluid from a sealed container: the FMVSS 116 label on every bottle tells you to keep it tightly closed to prevent absorbing moisture and not to refill the container. A half-used bottle that has sat open on a shelf for a year is not fresh fluid.

If you let the reservoir run dry during the bleed and air reaches the ABS hydraulic unit, the fix usually requires a scan tool to cycle the ABS pump while bleeding. That is the main way a DIY flush on this car goes wrong.

What to Check or Replace at the Same Time

A fluid flush puts you at every caliper, so it is the ideal time to inspect the rest of the system. Audi's schedules pair brake service with checking pad thickness, looking for leaks and damage, and checking the condition of the brake hoses.

• Pads and rotors - measure pad thickness and check the rotors for scoring and lip wear. If the rear brakes are due, a matched kit such as this Brembo OE rear disc brake kit for the 2010-2018 A8 quattro and S8 replaces rotors and pads together. For individual parts, browse our brake pads and brake rotors.
• Brake hoses - look for cracking, bulging or fluid seepage at the flexible hoses. Replace aged rubber hoses from our brake hose collection while the system is already open for bleeding.
• Calipers - a caliper that is leaking at the bleeder or piston seal, or a piston that will not retract, is best handled now. See our brake calipers.
• Hardware - new clips and slide hardware keep pads from dragging; our brake hardware kits cover that.

If you replace a caliper, hose or line, the system must be bled anyway, so do the full fluid change at the same time and reset the 2-year clock.

Frequently Asked Questions

What type of brake fluid does a 2010-2018 Audi A8 use?

DOT 4. Audi's A8 service information specifies new FMVSS 116 DOT 4 or SAE J1703 fluid, with the genuine Audi fluid sold under part number B 000 750. A quality low-viscosity DOT 4 that meets the same standards is also suitable.

How often should I change the brake fluid on an Audi A8?

Every 2 years regardless of mileage, per Audi's US maintenance schedules. Change it sooner if you drive aggressively, tow, or live somewhere humid.

How much brake fluid does an A8 hold?

Audi's 2011 A8 fluid chart lists the brake system at approximately 1.0 L (1.1 qt). Buy extra for a flush, since you push fluid through until it runs clean at every caliper.

Can I use DOT 3 in my Audi A8?

No. DOT 3's minimum boiling points are lower than DOT 4's under FMVSS 116, so it reduces the system's resistance to fade. Stick with DOT 4, and never use DOT 5 silicone fluid.

Can I mix low-viscosity DOT 4 with regular DOT 4?

Both are glycol-based, and Pentosin states its DOT 4 LV can be used in any vehicle that requires DOT 4. Mixing dilutes the better fluid's properties, though, so the right move is a complete flush with one fluid rather than topping off with another.

Is an A8 brake flush a DIY job?

It is manageable with a pressure bleeder and care. The risk is letting the reservoir run low and drawing air into the ABS unit, which may need a scan tool to purge. If you are not set up for that, a shop flush is quick.

Sources

1. Audi of America - 2011 A8 service information and fluid capacity chart (NHTSA) - DOT 4 / SAE J1703 spec, new fluid only, part number B 000 750, approx. 1.0 L brake system capacity
2. Audi of America - MY 2016 Maintenance Intervals, USA (NHTSA) - replace brake fluid every 2 years regardless of mileage, all vehicles including A8; brake system checks
3. Audi of America - MY 2019 Maintenance Schedule, All Models (NHTSA) - brake fluid change every 2 years regardless of mileage; hose, leak, bleeder cap and pad checks
4. 49 CFR 571.116 - FMVSS No. 116, Motor vehicle brake fluids - DOT 3/4/5 boiling point and -40 viscosity minimums; container labeling
5. Pentosin DOT 4 LV product data sheet - LV boiling points and viscosity, Audi/VW B 000 750 cross-reference, usable where DOT 4 is required
6. Audi owner's manual - Brake fluid - fresh fluid only, moisture absorption and corrosion, vapor lock, toxicity and paint warnings