Audi S6
4.0-litre TFSI V8 BiTurbo with 450 PS (EA825). Prone to oil strainer contamination — regular oil changes every 10,000 km are mandatory. High-pressure pump pressure piece wears at higher mileage; uprated version available. Tiptronic shift issues documented from 150,000 km.
Last V8-powered S6 — the community knows, prices are rising
420 hp twin-turbo V8, honey-smooth and brutal at the same time. The last S6 with eight cylinders — PistonHeads calls it 'last chance to get a V8'. Used prices climbing since the C8 only offers a V6. Cold start sounds like a subtle thunderclap. Running costs are real, but so is the character.
Engine Weaknesses 5
Turbocharger damage occurs frequently on the 4.0 TFSI V8 and is attributed to insufficient oil supply. First signs often appear from 60,000–80,000 km with power loss and noise.
Symptoms: Power loss, whistling or howling noises, elevated oil consumption, blue smoke
The aluminium block with coated cylinder bores does not allow conventional oversize piston repair. Damage requires expensive engine replacement or complete overhaul.
Symptoms: High oil consumption, power loss, blue smoke, combustion noise
The S-Tronic dual-clutch gearbox is the weakest link in the S6 C7 drivetrain. Aggressive driving and power fluctuations at higher rpm put additional strain on the DCT.
Symptoms: Jerk on gear changes, clutch slip, overheating warning, failed shifts
Above 2,500 rpm piston cooling jets spray oil against the pistons. Some of this oil burns. Spirited driving can increase consumption to 1–2 litres per 1,000 km noticeably.
Symptoms: Dropping oil level, no externally visible oil loss, normal engine behaviour
S6 and RS6 share the known engine mount wear problems. Heavily loaded mounts become porous and transmit vibrations into the passenger compartment.
Symptoms: Noticeable vibrations in the cabin, droning noise on load change
Vehicle Weaknesses 9
On model years 2015–2018, the locking bolt of the tow bar can fracture, potentially causing the trailer to become detached while driving. Free workshop visit required.
The Multitronic CVT gearbox has a notoriously poor reliability record. Improved on the C7, it remains a risk. Total failure possible from 100,000 km; repair is very costly.
A material defect can cause the camshafts in the 3.0 TDI to fracture, leading to engine damage. Mainly affects vehicles from model year 2014 to early 2017.
The optional air suspension (AAS) is prone to failure through porous air bellows and defective compressors. Repair costs of 600–1,800 EUR per corner are possible.
LED headlights fail due to defective control modules or individual LEDs. Repair is often more expensive than replacement, as modules cannot be replaced individually.
The automatic climate control shows malfunctions from around 60,000 km: incorrect temperature regulation, blower stage issues or complete failure of individual zones on the three-zone system.
Wheel bearings, particularly at the rear axle, show increased wear at higher mileages. Regularly flagged on vehicles from 80,000 km.
On the C7, rust occurs primarily on the underbody and sills, sometimes in hard-to-reach areas. On vehicles over 7 years old, the underbody should be thoroughly inspected.
On V6 and V8 engines, engine mounts often wear from around 50,000 km, causing noticeable vibrations.