Every Tank in the Range: Petrol in a Diesel Mercedes
How much of the fuel in your tank is currently petrol hinges on how big the tank is on your car, once you've put petrol in a diesel Mercedes. We set out the fuel tank capacity for every diesel Mercedes model here, and each one has its own page too, linked further down.
Petrol in Diesel empties the car where it stands, however big the tank is, so the guidance is to keep the engine turned off then phone us once you realise what has happened.
What each diesel Mercedes holds in its tank
The model and its variant settle how much the fuel tank takes on a diesel Mercedes, from 50 litres up to 100 litres across the range.
The C-Class holds as much as 66 litres.
In our figures, the tank on the SLK takes 60 litres at the most.
There are 215 versions across the 18 diesel Mercedes models we cover, and every model gets a page giving the tank on each one.
Does a tiny amount of wrong fuel in your Mercedes matter?
The proportion of petrol depends on how full the tank was before you refuelled. That is because wrong fuel in your Mercedes blends with whatever diesel was already in it. When a couple of litres of petrol go into a tank running near empty, they form far more of what the engine would draw. On top of a nearly full tank of up to 100 litres, the same amount is just a small part of the total.
Drivers often ask how much petrol is too much. It is more helpful to find out whether the engine has run, as a running engine is what draws the mixture from your tank and sends it through the fuel pump to the fuel injectors.
A drain is normally all the car requires when the quantity is modest.
Diesel Mercedes engines and the badges
Across the diesel Mercedes models in our data, the badges read CDI, BlueTEC and TD.
Starting at 1.7 litres, engine sizes in the range run to 3.0 litres.
Before you ring, it's worth checking the badging on the back and the model name, since they show us which one you drive. Being unsure does not matter. Call anyway, and we'll figure it out with you.
What happens with AdBlue in a diesel Mercedes
Fuel tank size does not matter with AdBlue. With AdBlue in a diesel Mercedes, the diesel already in the tank cannot thin it. Being mostly water, AdBlue keeps separate from the diesel and settles to the bottom, which is where the fuel pump draws from. Even a tiny quantity ends up in your fuel lines.
As the water in AdBlue evaporates, the urea left behind forms crystals in the fuel lines and the fuel filter, and AdBlue doesn't burn or give the fuel pump any protection either.
If a diesel car carries a separate AdBlue tank, its filler is commonly alongside the diesel one under the same fuel flap, with a blue filler cap and a narrower nozzle.
What a fuel drain on your Mercedes takes
The entire tank is cleared in a fuel drain on your Mercedes, however large it is in your car, without the vehicle being moved from where it stands. Fresh diesel goes in after the contaminated fuel has been pumped out and the lines and your filter are purged, and then the fuel system is primed and your engine fired up.
The CLS, for example, carries a fuel tank holding up to 80 litres.
Fresh diesel is what the vehicle runs on after this drain is finished, so you can drive it away.
Clearing the tank: AdBlue removal from a diesel Mercedes
Draining your tank fully is where AdBlue removal from a diesel Mercedes starts, because AdBlue doesn't mix in and sinks to the base instead. If the motor has run, we flush the lines and your filter through as well and change the fuel filter where needed.
This covers AdBlue that has gone into the diesel tank, not taking out or turning off the AdBlue system on the car.
Pricing a fuel drain on a diesel Mercedes
Two call-outs on the same model can be quite different, so we do not list a fixed price. Whether the car has been run or driven affects it most. After that it rests on how much was put in against the tank size, whether petrol or AdBlue got in, and where the car is. We can tell you what is involved in this job if you phone with those details.
Tank questions about petrol in a diesel Mercedes
What diesel Mercedes model has the biggest fuel tank?
Our figures put the biggest tank on the S-Class, which holds up to 100 litres, with the smallest on the E-Class.
With a bigger tank, is petrol less of an issue?
In a larger tank, petrol makes up a smaller part of the total, yet it hasn't gone anywhere, and it reaches the pump as soon as your engine runs. A drain removes all of it as long as the car stays switched off.
Which page shows the tank for my precise version?
Every version we hold data for is listed alongside its tank on the page for your model, which is linked further down.
Wrong fuel in my Mercedes: what does that cover?
Just diesel goes in the diesel tank. Petrol of any type, super unleaded included, is wrong fuel, and so is AdBlue, which goes in a tank of its own.