Petrol in a Diesel BMW 6 Series: What the Tank Holds
If you have put petrol in a diesel BMW 6 Series, the capacity of its tank is among the first things to know, since it determines how much of what is in there is currently petrol. This page lists the tank size for every version of the BMW 6 Series we keep figures for, together with the motors it came with.
The guidance doesn't vary with the number once it has happened. With the motor kept off, phone Petrol in Diesel and the car will be drained where it stands.
BMW 6 Series fuel tank capacity, version by version
70 litres is what the diesel tank holds on each version of the BMW 6 Series we have figures for, because they all share the same tank.
| Version | Fuel tank |
|---|---|
| BMW 635d Cabrio | 70 litres |
| BMW 635d Coupe | 70 litres |
| BMW 640d Cabrio | 70 litres |
| BMW 640d Coupe | 70 litres |
| BMW 640d Gran Coupe | 70 litres |
| BMW 640d xDrive Cabrio | 70 litres |
| BMW 640d xDrive Coupe | 70 litres |
| BMW 640d xDrive Gran Coupe | 70 litres |
What a few litres means for wrong fuel in your BMW 6 Series
The proportion of petrol rests on how full the tank was before you refuelled. That is because wrong fuel in your BMW 6 Series blends with whatever diesel was still in there. Up to 70 litres go in the tank. Filling an almost full one with a couple of litres of unleaded means only a small share of petrol in the whole, whereas the same quantity in a nearly empty tank makes up much more of what the motor would take in.
Often, people want to know at what point the petrol becomes too much. The more helpful thing to find out is if the motor has run, since starting it is what moves the mixture from the tank and through the pump and your injectors.
A fuel drain is the right option no matter what the proportion, and with a small quantity it is usually all your 6 Series needs.
Which engines your diesel 6 Series came with
The motor in your 6 Series shows in the version name on the badge. Note it before you call.
The data additionally include Coupe and xDrive versions of the 6 Series.
Ring anyway if you are not sure which version you have, then we'll figure it out with you.
Tank size and AdBlue in a diesel BMW 6 Series
With AdBlue, tank size plays out differently. The fuel pump takes its fuel from the base of your tank, and that's where AdBlue sinks, and so even a tiny amount reaches your fuel line. If you have AdBlue in a diesel BMW 6 Series, your diesel around it doesn't dilute it, since AdBlue is mostly water and does not mix with diesel.
AdBlue does not combust and gives the pump no protection, and as its water evaporates, the urea left behind forms crystals in your lines and the filter and corrodes the metal next to it.
Certain diesel cars carry AdBlue in a second tank with its own filler, commonly next to the diesel one under the same fuel flap. If your 6 Series has an AdBlue filler, the diesel nozzle is the larger of the two, and the AdBlue cap is usually blue.
A fuel drain on your BMW 6 Series, step by step
Whatever size your tank is on your version, a fuel drain on your BMW 6 Series empties the lot, just where the vehicle is sitting. We draw the contaminated fuel out, rinse the fuel lines and the fuel filter, and fill up again with clean diesel ahead of priming your system and firing up the motor.
Left at home or still at the pumps, your 6 Series receives the same job. Once this drain is done it is running on fresh diesel and you can drive it away.
How AdBlue removal from a diesel BMW 6 Series works
With AdBlue sitting at the bottom of your tank and not blended in, AdBlue removal from a diesel BMW 6 Series starts by clearing the tank fully. Where your engine has been started, your lines and the fuel filter are rinsed through as well, and your fuel filter is replaced if necessary.
This covers AdBlue that has gone into the diesel tank. It's not taking out or turning off the AdBlue system on the car.
How the price of a fuel drain on the BMW 6 Series is worked out
We don't give a fixed price, because two jobs on the same model can be very different. How much was put in compared with the size of your tank, petrol or AdBlue, and the car's location all count, yet whether the 6 Series has been driven or just started changes it most.
Call with those details so we can explain what this job will involve.
Your tank queries on petrol in a diesel BMW 6 Series
Fuel tank capacity of the BMW 6 Series: how much does it take?
The same tank is fitted to each version in our figures, holding 70 litres.
Does a larger tank make petrol less of a worry?
That petrol is still there in a bigger tank, and still gets to the pump once the engine runs, even though a few litres form less of the total. All of that comes out with a fuel drain, as long as your 6 Series is switched off.
How many diesel versions of the 6 Series do you cover?
There are 8 diesel 6 Series versions in our data, and the model name on your badge tells you which row of the table above is yours.
Wrong fuel in my BMW 6 Series: what does that include?
It means anything put into the diesel tank that's not diesel, so petrol of any type, even super unleaded, or AdBlue, which has its own dedicated tank.
Can you drain the BMW 6 Series wherever it is?
Yes, we can. We travel to your car, whether it is still at the station forecourt or parked at home, so it doesn't need to be shifted or started.