Petrol in a Diesel Mercedes GL? Start With the Tank
Once you have got petrol in a diesel Mercedes GL, the capacity of its fuel tank is among the first things to know, since it settles how much of what is in there is currently petrol. The tank size and the engines are listed on this page for every Mercedes GL version that we have figures for.
When it has occurred, the same advice applies whatever the size happens to be. With your engine left off, ring Petrol in Diesel and the car can be drained where it is.
Mercedes GL fuel tank capacity, by version
The Mercedes GL carries the same diesel tank across each version we have data for, and it holds 100 litres.
| Version | Fuel tank |
|---|---|
| Mercedes GL 320 CDI | 100 litres |
| Mercedes GL 350 CDI | 100 litres |
| Mercedes GL 350 CDI BlueTEC | 100 litres |
| Mercedes GL 350 CDI BlueTEC 4-MATIC | 100 litres |
| Mercedes GL 420 CDI | 100 litres |
A few litres of wrong fuel in your Mercedes GL, and what they mean
Wrong fuel in your Mercedes GL blends with whatever diesel is still in your tank, and so the proportion of it that is petrol rests on how full the tank was when you filled up. When a couple of litres of petrol go into a tank sitting close to empty, they make up a much greater share of what the engine would take in. Added to an almost full tank of up to 100 litres, the same amount is just a small share of the whole.
Drivers often want to know how much petrol counts as too much. It is more useful to know whether the engine has run, since a running motor is what takes that mixture out of your tank and through your pump and the injectors.
Having it drained is the sensible course whatever the proportion is. If the amount is small, your GL usually needs nothing more than that.
Engines fitted to the diesel GL
Before you ring, it is worth noting the version name on the badge, since it tells us which engine your GL has.
Diesel versions of the GL in our data wear CDI and BlueTEC badging.
More of them wear the CDI badge than any other badge, though the GL 350 CDI BlueTEC wears the BlueTEC badge instead.
When you are not sure which version you own, call anyway then we will work it out together.
Tank size and AdBlue in a diesel Mercedes GL
AdBlue changes what the capacity of the tank means. AdBlue is largely water and doesn't mix with diesel, and so with AdBlue in a diesel Mercedes GL, your diesel surrounding it does nothing to weaken it. Because it sinks to the base of the tank, where the fuel pump draws from, even a small amount gets into the fuel lines.
Nothing in AdBlue combusts, and the pump gets no lubrication from it. Once its water evaporates, urea is left in your lines and the filter as crystals, and the metal next to it is eaten into.
Certain diesel vehicles hold AdBlue in a second tank with its own filler, frequently alongside the diesel one under the same fuel flap. On any GL with an AdBlue filler, a blue cap generally marks it, and that cap accepts a narrower pump nozzle than the diesel one.
How a fuel drain on your Mercedes GL works
Whatever size the tank is on your version, a fuel drain on your Mercedes GL empties the lot, just where the car is standing. Clean diesel is put in after the tainted fuel is pumped out and the lines and your filter are purged, and then the system is primed and your engine fired up.
Whether your GL is still at the station forecourt or parked on your drive does not change anything. You can drive it away after the drain is done, and it will be running on clean diesel.
What AdBlue removal from a diesel Mercedes GL involves
Emptying your tank totally is where AdBlue removal from a diesel Mercedes GL starts, as AdBlue does not mix in and collects at the base instead. Where the motor has been started, the fuel lines and the fuel filter are rinsed through as well, and the filter is changed if needed.
What this covers is AdBlue that ended up in the diesel tank, not removing or switching off the AdBlue system on the car.
The cost of a fuel drain on the Mercedes GL
We don't give a fixed price, since two call-outs on the same model can be rather different. What changes it most is whether the GL has been started or driven, and next how much got in compared with the size of your tank, whether it was petrol or AdBlue, and where the car is.
With those details, we can let you know what the job will involve when you call.
Petrol in a diesel Mercedes GL: tank queries
Fuel tank capacity of the Mercedes GL: how much does it hold?
100 litres, with every version we have figures for using the same tank.
Is petrol less of a problem in a larger tank?
The petrol is still there in a bigger tank, and still gets to your pump once the engine runs, even though a couple of litres make up less of the total. All of that comes out with a drain, as long as your GL is switched off.
How many diesel versions of the GL do you cover?
Your badge tells you which of the 5 diesel versions of the GL in the table above is yours, since we have figures for each.
What counts as wrong fuel in my Mercedes GL?
Just diesel belongs in your diesel tank. Petrol of every grade, super unleaded included, is wrong fuel, and so is AdBlue, which goes in a tank of its own.
Can you drain the Mercedes GL where it is?
Yes. We come to the vehicle, whether it's still on the station forecourt or left at home, so it doesn't need to be moved or started.