Petrol in a Diesel Audi A7: What the Tank Holds
Once you have got petrol in a diesel Audi A7, the size of its fuel tank is one of the earliest things to know, as it determines how much of what is in there is currently petrol. Each version of the Audi A7 we hold figures for is on this page alongside its tank size, and the same goes for the motors it was sold with.
After it has occurred, the same advice applies whatever the figure happens to be. Leave the engine off and call Petrol in Diesel, and we'll come out and empty the car where it is.
How each version stacks up on Audi A7 fuel tank capacity
The Audi A7 carries the one diesel tank on every version we hold data for, and it holds 65 litres.
| Version | Fuel tank |
|---|---|
| Audi A7 Sportback 3.0 TDI | 65 litres |
| Audi A7 Sportback 3.0 TDI quattro | 65 litres |
Does a little quantity of wrong fuel in your Audi A7 count?
How full the tank was when you filled up determines the proportion of petrol, because wrong fuel in your Audi A7 blends with whatever diesel is still in it. Up to 65 litres go into your tank. Topping up an almost full one with a few litres of petrol leaves just a small share of petrol in the whole, whereas the same amount in a nearly empty tank makes up far more of what the engine would draw.
Motorists commonly ask how much petrol is too much. The more helpful point to find out is if your engine has been run, because starting the engine is what carries that mixture from the tank and through the pump and the fuel injectors.
With a small quantity, a drain is normally all your A7 needs, and whatever the share, getting it drained is the safe thing to do.
The engines on the diesel A7
Before you phone, it is worth checking the version name on the badge, as it tells us which motor your A7 has.
Across the diesel A7 versions in our figures, the badges read TDI.
The motors are each 3.0 litres.
There are Sportback A7 versions in the figures as well.
When you're not certain which version you have, ring anyway and we will figure it out together.
AdBlue in a diesel Audi A7
With AdBlue, tank size works differently. AdBlue is mostly water and does not mix with diesel, and so with AdBlue in a diesel Audi A7, the diesel around it does nothing to thin it. Since it sinks to the bottom of the tank, where the fuel pump draws from, even a tiny volume reaches your fuel lines.
AdBlue doesn't combust and gives the pump no lubrication, and as its water evaporates, the urea left over crystallises in the lines and the filter and attacks the metalwork next to it.
On some diesel cars, AdBlue has a separate tank of its own, and its filler frequently is next to the diesel filler under the same fuel flap. Where your A7 has an AdBlue filler, its filler cap is normally blue and takes a slimmer pump nozzle than the diesel filler.
A fuel drain on your Audi A7, step by step
Done where your car is parked, a fuel drain on your Audi A7 clears the entire tank, whatever size it is on your version. Drawing out the contaminated fuel happens first, then a rinse of the lines and your fuel filter. Then we refill with fresh diesel, prime the fuel system and fire up your engine.
Still at the forecourt or sitting on your drive, your A7 can be drained just the same. When we finish the drain, your car is running on fresh diesel and ready to drive away.
How AdBlue removal from a diesel Audi A7 works
Clearing your tank fully is where AdBlue removal from a diesel Audi A7 starts, since AdBlue doesn't blend in and settles at the bottom instead. If the engine has been started, we rinse the lines and your filter through as well and replace the fuel filter if it needs it.
Removing or turning off the AdBlue system on the vehicle is not what this covers. It's about AdBlue that has got into your diesel tank.
Pricing a fuel drain on the Audi A7
The same model can mean quite different call-outs, which is why we don't list a fixed price. What affects it most is whether the A7 has been started or driven, and after that how much went in against the capacity of the tank, whether it was petrol or AdBlue, and where your car is now.
Those facts are what we need to tell you what the work involves. Call with them to hand.
Tank questions about petrol in a diesel Audi A7
Fuel tank capacity of the Audi A7: how much does it take?
Every version we have data for shares one tank, and it takes 65 litres.
Does a larger tank make petrol less of a problem?
A bigger tank means a few litres make up less of the whole, but the petrol is still in there and still reaches your pump when your engine runs. All of it comes out with a fuel drain, as long as your A7 is switched off.
Diesel versions of the A7: how many do you list?
There are 2 diesel A7 versions in our data, and the model name on your badge shows which row of the table above is yours.
Which fuels, other than diesel, would be wrong fuel in my Audi A7?
It means everything put into your diesel tank that is not diesel, and so petrol of any grade, even super unleaded, or AdBlue, which has its own separate tank.
Will you drain the Audi A7 where it stands?
There is no reason to move or start the vehicle. Whether it's parked at home or still at the station forecourt, we travel to it.