Audi A6 C8 40 TDI Service Schedule

Driving an Audi A6 C8 40 TDI and wondering what needs changing, when to do it and which parts to choose? I get asked this all the time. It's a big, quiet, economical car, and the dashboard says "Service due in 30,000 km". So you think there's nothing to worry about until then. Well, not quite! 🙂 I want to save you from some nasty surprises, so I've put together the factory service schedule and my own recommendations, based on what we've learnt looking after these cars at Das Auto Service.

Here's exactly which models we're talking about:

• Audi A6 C8 Saloon and Avant (2018–2025), including the 2023 facelift onwards
• 2.0 TDI engine, 204 hp (150 kW) and 400 Nm, most commonly engine codes DFBA and DTPA
• 7-speed S tronic dual-clutch gearbox
• Front-wheel drive or quattro ultra
• DPF, SCR system with AdBlue and mild hybrid system (MHEV)

You'll find your engine code on the sticker in the boot and in your service book. Check it before ordering any parts. That little code tells you exactly which oil your engine needs and which replacement kits will fit your car.

What engine oil does the Audi A6 C8 40 TDI need?

This TDI has a DPF, so it needs low-ash engine oil that meets the exact specification in your service book. For these engines, that's usually VW 507 00. At Das Auto Service, we check the engine code first and only then fill it with genuine oil that meets the correct specification. We don't just pour in whatever's left in an old container, and we certainly don't mix up a cocktail of different oils.

The factory LongLife service schedule allows up to 30,000 km or 2 years between oil changes. But do you know what I recommend? Not 20,000, not 30,000, but every 10,000 km or once a year, whichever comes first, regardless of the oil you use! Here in Bulgaria, we drive through dust, sit in traffic jams, start our engines in freezing winter weather and run them in high summer temperatures. When the DPF regenerates, extra fuel is injected, and some of it can end up in the engine oil. That dilutes the oil and makes it deteriorate without you noticing anything wrong. Today, your car might be running beautifully. Tomorrow, you could be the one paying the bill.

Which filters need changing, and when?

• Oil filter – every time you change the engine oil. No exceptions.
• Crankcase ventilation filter – every 80,000 km.
• Fuel filter – I recommend changing it together with the engine oil every 10,000 km or once a year, whichever comes first. Diesel fuel in Bulgaria isn't always as clean as we'd like, and the TDI's fuel system really doesn't like dirt.
• Air filter – we change it together with the engine oil every 10,000 km or once a year, whichever comes first, and inspect it at every check-up. With our driving conditions, we don't wait for the factory interval.
• Cabin filter – we change it together with the engine oil every 10,000 km or once a year, whichever comes first.

How should you service the S tronic in your A6 40 TDI?

Your A6 has a 7-speed S tronic dual-clutch gearbox. You've probably heard someone say the gearbox oil is "filled for life". Believe me, I hear that one all the time. But there's no such thing as oil that never ages. That's why, at Das Auto Service, we change the S tronic oil every 60,000 km, using genuine oil only. Afterwards, we always carry out clutch adaptation so the clutches work properly. We don't wait until the DSG starts banging into gear or jerking. We do it every single time.

But what if your gearbox is already jerking when you pull away, banging into gear in traffic or behaving strangely while you're parking? First, we connect the diagnostic equipment. We read the fault codes and check the live data. We don't immediately order a new mechatronic unit, the gearbox's electronic brain, just because somebody has guessed that it's the problem.

What if your A6 has quattro ultra?

With quattro ultra, your car drives on the front wheels most of the time. When needed, a clutch engages the rear axle too. That helps save fuel. But here's the important bit! It doesn't mean the system is maintenance-free. It has its own oil, which needs changing every 30,000 km. We check it at every inspection. We don't wait for it to start whining or for a warning light to appear on the dashboard before paying attention to it.

Does the A6 C8 2.0 TDI have a timing belt or a chain?

A timing belt. My advice is to replace it every 180,000 km or 5 years, whichever comes first. And I don't mean just the belt. I mean the complete genuine timing belt kit, including the rollers, tensioner and water pump. Why do I pay attention to the years as well? Because rubber ages whether you're driving 30,000 km a year or your A6 spends most of its life in the garage. And if that belt snaps, the valves meet the pistons. At that point, we're no longer talking about a timing belt change. We're talking about a major engine repair, and you're the one who'll have to pay for it. I've explained exactly what's included in the genuine kit in my article about the timing belt kit with water pump.

What should you know about AdBlue and the DPF?

Top up the AdBlue when your car tells you it's time. Always use fluid from a sealed container, and be careful not to get any dust into the filler opening. At every inspection, we check the system's sensors and heater. Don't underestimate how important they are.

Advice from Kris Mladenov: Don't ignore the AdBlue warning. Once your car starts counting down the remaining kilometres and the counter reaches zero, you won't be able to restart the engine after switching it off.

And what about the DPF? It really doesn't like a life spent entirely in town. If your A6 spends most of its time in city traffic, take it out for a longer drive regularly so the filter has a chance to regenerate. And no, removing the DPF or EGR valve isn't the answer. We don't remove them. We find what's causing the problem and fix it properly. I've explained more in my article about the DPF in city driving.

When should you change the brake fluid, coolant and glow plugs?

We change the brake fluid every 2 years. Over time, it absorbs moisture, which lowers its boiling point. Under heavy braking, the pedal can start to feel spongy. Exactly when you need your brakes the most. That's why we test the fluid with proper equipment instead of just looking at it and deciding the colour seems fine.

We change the coolant every third heating season, and every autumn we check how well it's protecting the engine. Over time, the additives lose their effectiveness, and tiny pits can start forming in the aluminium engine block. The nasty part is that you usually don't find out until something starts leaking.

We test the glow plugs every autumn. If your car struggles to start on cold mornings, shakes or the glow plug warning light flashes, don't wait until winter really sets in. Find out what's wrong early, before it turns into something more serious.

What about the air conditioning and tyre repair kit?

Every spring, I recommend having your air conditioning checked and changing the cabin filter. And I don't mean just letting someone "regas the air con" without even checking whether it needs it. There's something else that's easy to forget. If your A6 has a compressor and tyre sealant bottle instead of a spare wheel, check the expiry date on that bottle. Once a year. Because the last thing I want is for you to discover it's expired just when you've got a flat tyre.

Why do I recommend a check-up every 6 months?

At Das Auto Service, I want our customers to get into one simple habit: bring the car in for a check-up every 6 months. We check the fluids, look for leaks and inspect the brake pads, discs, tyres and suspension. We also run a diagnostic scan of every control module. Why am I so insistent? Because I've seen far too many expensive repairs that started with something tiny. A small leak, a stored fault code, something we could have caught early. But nobody had bothered to look.

What should you remember about servicing your A6 C8 40 TDI?

1. Engine oil meeting the specification in your service book, plus the oil filter – every 10,000 km or once a year, whichever comes first, regardless of the oil used.
2. Fuel, air and cabin filters – we change them together with the engine oil every 10,000 km or once a year, whichever comes first, and inspect them at every check-up.
3. S tronic – oil change every 60,000 km, always followed by clutch adaptation.
4. quattro ultra – oil change every 30,000 km and inspection at every check-up.
5. Timing belt, rollers, tensioner and water pump – every 180,000 km or 5 years.
6. Brake fluid – every 2 years. Coolant – every third heating season.
7. Full vehicle check-up – every 6 months.

My advice to you is simple: when it comes to your A6 40 TDI, there are just 2 things I really want you to take seriously. First, don't choose a workshop purely because it offers the lowest price. Find people who can explain what they're doing to your car and why. Second, use genuine parts and consumables only. Yes, you'll spend around 20% more, but I believe the peace of mind is worth it. If you'd like us to look after your A6 at Das Auto Service, you can book an appointment for routine servicing or for gearbox servicing. And if your A6 has a V6 engine, have a look at the A6 C8 3.0 TDI service schedule. I've also put together the Q5 FY 2.0 TDI service schedule.

I'm Kris Mladenov, and I believe that if I know something that could help you, I should share it. That way, more people can look after their cars properly. I hope you now have a much clearer idea of when and how to service your A6. And if this article has helped you, send it to a friend who drives an A6 too.

The solution from our shop

Genuine LongLife III FE 0W-30 engine oil, 5 litres

Genuine LongLife III FE 0W-30 engine oil – meets the specification for the 2.0 TDI with DPF.

View in our shop

Genuine S tronic dual-clutch gearbox oil G052529A2, 1 litre

Genuine G 052 529 oil for the S tronic dual-clutch gearbox.

View in our shop

Genuine VAG AdBlue® fluid G052910M4, 10 litres

Genuine AdBlue fluid for the SCR system.

View in our shop

Genuine VAG G12evo coolant G12E050A2, 1.0 litre

Genuine G12evo coolant – change it every third heating season.

View in our shop

Genuine VAG DOT 4 brake fluid B000750M3, 1 litre

Genuine DOT 4 brake fluid – change it every 2 years.

View in our shop

Read more

• Routine servicing
• Gearbox servicing
• Audi A6 C8 3.0 TDI service schedule
• Audi Q5 FY 2.0 TDI service schedule
• Timing belt kit with water pump: what's included in the genuine kit
• DPF in city driving: how to stop it clogging up
• Audi A4 B9 2.0 TDI service schedule

Frequently asked questions

What engine oil does the Audi A6 C8 40 TDI need?

Low-ash oil meeting the specification in your service book, usually VW 507 00. I recommend changing it every 10,000 km or once a year, whichever comes first, always together with the oil filter.

Does the A6 C8 40 TDI have a timing belt or a chain?

A timing belt. I recommend replacing it every 180,000 km or 5 years, whichever comes first, using a genuine kit with the belt, rollers, tensioner and water pump.

When should I change the S tronic oil in my A6 40 TDI?

Every 60,000 km, using genuine oil only. After every oil change, we carry out clutch adaptation, even if the gearbox is working perfectly normally.

What happens if my Audi runs out of AdBlue?

The car starts counting down the remaining kilometres. Once the counter reaches zero, you won't be able to restart the engine after switching it off. So top up in good time, using AdBlue from a sealed container.