The 4.0 TFSI V8 is the heart of the RS6, RS7, S6, S7 and S8. Two turbos, enormous torque and an engine note you won't forget in a hurry. What an engine! But there's something I want you to understand about 4.0 TFSI V8 common problems. Things get seriously hot under there, and this engine won't forgive neglected servicing. Let me show you what we look for in the workshop and what you need to keep an eye on if you drive a 4.0 TFSI.
Why are the turbos in the middle of the engine?
The two turbos sit between the cylinder banks, right inside the V of the engine. That gives the exhaust gases the shortest possible route to the turbos, so the moment you put your foot down, the car responds almost instantly. Brilliant, isn't it? But that's also where the heat is most intense. The oil, hoses and seals around the turbos are constantly exposed to extreme temperatures. And as the years go by, that heat starts taking its toll.
What are the 4.0 TFSI V8 common problems we watch for?
- Oil consumption — as the mileage builds up, the engine can start using more oil because of wear in the seals and turbos.
- Turbo oil pipes — over time, their seals age and start causing trouble.
- Cooling system — the pumps, hoses and thermostat are constantly working against those high temperatures.
- Spark plugs and ignition coils — with that much power, they're under some serious strain.
- Engine mounts — we always make sure to check those too.
How often should you change the engine oil?
With the 4.0 TFSI, engine oil is not something to take lightly. For cars driven in Bulgaria, I recommend changing the engine oil and oil filter every 10,000 km or once a year, whichever comes first, regardless of the oil used. And always use oil that meets the correct specification for your engine. Why am I so firm about this? Because those two turbos work in incredible heat, and old oil does them no favours at all. This is one area where cutting corners on servicing simply isn't worth it.
What about the gearbox?
These cars have an eight-speed Tiptronic. It's a seriously tough gearbox, but don't assume that means it doesn't need servicing. There's a lot of power, the cars are heavy, and the gearbox has to cope with a tremendous amount of load. That's why the oil needs changing. And after every gearbox service, we always carry out an adaptation to make sure everything works as it should.
After a spirited drive, don't switch the engine off straight away. Let it idle for about a minute so the turbos can cool down. If you shut it off immediately, the oil inside the turbos can overheat and burn, damaging the bearings. Then you're looking at an expensive repair. And my friend, you're the one who ends up paying the bill.
Why is the coolant so important?
When an engine runs this hot, the cooling system is absolutely vital. We recommend changing the coolant every third heating season. As it ages, it loses its protective properties, and tiny pits of corrosion can start forming in the aluminium. So don't wait until the temperature gauge starts climbing before you remember the coolant needs attention.
A tip from Kris Mladenov: Keep track of how much oil you're topping up between changes. If you notice the engine starting to use more, bring the car in and let us have a look. It's much better to catch a problem early than leave it until it turns into something serious.
If you drive an RS6, RS7, S6, S7 or S8 with the 4.0 TFSI, come and see us at Das Auto Service. We know this engine well, and we know exactly where to look. We'll check how it's doing and tell you what genuinely needs attention. No unnecessary repairs and no replacing parts on a guess. Because when the diagnosis is wrong, it's not the workshop that ends up paying. It's you.
The solution in our shop
Genuine Longlife III FE 0W30 engine oil 5L
Genuine engine oil meeting the specification for the 4.0 TFSI. Change it every 10,000 km or once a year, whichever comes first.
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Genuine automatic gearbox transmission oil 1L
Genuine transmission oil for the eight-speed Tiptronic.
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Genuine VAG G12Evo coolant G12E050A2 1.0l
Genuine G12evo coolant. I recommend changing it every third heating season.
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Frequently asked questions
Is it normal for the 4.0 TFSI to use oil?
Yes, a little oil consumption can be normal. But if you notice it's starting to use more, we need to check the turbos and seals. Don't just leave it, my friend.
How often should I change the oil in my RS6?
I recommend every 10,000 km or once a year, whichever comes first. With this engine, I wouldn't risk leaving it any longer.
Does the Tiptronic gearbox in my RS6 need servicing?
Yes, absolutely. The oil in the eight-speed Tiptronic needs changing, and afterwards we carry out a gearbox adaptation.