Petrol in a Diesel BMW 7 Series? Start With the Tank
How much petrol there now is in that blend depends on the tank, so its capacity is well worth checking straight away if you've put petrol in a diesel BMW 7 Series. This guide gives the tank for every version of the BMW 7 Series we have figures for, plus the engines it came with.
Regardless of how big the figure is, there's a single piece of advice after the event. Keep your engine off then call Petrol in Diesel, and we'll come over to empty the vehicle where it sits.
How every version compares on BMW 7 Series fuel tank capacity
Versions of the BMW 7 Series vary, and so the diesel tank holds anywhere from 80 to 88 litres depending on yours.
Of the versions in our figures, the 745d has the biggest tank, with the smallest on the 750Ld xDrive.
The 740d xDrive holds 80 litres, for comparison.
For the 725tds, the capacity is 85 litres.
| Version | Fuel tank |
|---|---|
| BMW 725tds | 85 litres |
| BMW 730d | 85 litres |
| BMW 730d xDrive | 80 litres |
| BMW 730Ld | 88 litres |
| BMW 740d | 85 litres |
| BMW 740d xDrive | 80 litres |
| BMW 745d | 88 litres |
| BMW 750d xDrive | 80 litres |
| BMW 750Ld xDrive | 80 litres |
A couple of litres of wrong fuel in your BMW 7 Series, and what they mean
Whatever diesel is already in your tank blends with the wrong fuel in your BMW 7 Series, and how full it was when you filled up determines how much of the mixture is petrol. When a couple of litres of unleaded are put into a tank sitting close to empty, they form a far larger share of what the engine would take in. Added to a nearly full tank of up to 88 litres, the same volume is only a small share of the total.
Motorists frequently wonder how much petrol is too much. Whether the motor has been run is the more useful point to check. Once it runs, the pump draws that mix from your tank and passes it on to the fuel injectors.
A fuel drain is the right option no matter what the proportion, and with a small volume it's generally all your 7 Series needs.
Diesel 7 Series engines and their badges
When you phone, it is useful to have checked the badge beforehand, as the name of the version on it shows us which motor your 7 Series has.
There are xDrive 7 Series versions in the figures too.
If you're not sure which version you drive, ring all the same and we will work it out together.
AdBlue in a diesel BMW 7 Series
Where AdBlue is concerned, the tank size counts differently. AdBlue is largely water and doesn't blend with diesel, and so with AdBlue in a diesel BMW 7 Series, the diesel surrounding it does nothing to weaken it. Because it sinks to the base of your tank, where the fuel pump draws from, even a small volume reaches your fuel lines.
AdBlue gives your pump no lubrication and will not combust. Its water evaporates as it stands, leaving urea that crystallises in the fuel filter and your lines, where it attacks the metal it touches.
A second tank with a dedicated filler holds the AdBlue on some diesel vehicles, commonly beside the filler for diesel under the same flap. Where your 7 Series has an AdBlue filler, its filler cap is generally blue and takes a smaller nozzle than the diesel one.
A fuel drain on your BMW 7 Series, step by step
The whole tank is emptied in a fuel drain on your BMW 7 Series, however big it is in your version, without your car being moved from where it stands. Drawing out the tainted fuel happens first, followed by a flush of the fuel lines and your fuel filter. Then we refill with clean diesel, prime your system and start your engine.
Left at home or still at the pump, your 7 Series gets the same job. After we finish this drain, the car is running on clean diesel and ready to drive away.
What AdBlue removal from a diesel BMW 7 Series involves
With AdBlue lying at the bottom of your tank rather than blended in, AdBlue removal from a diesel BMW 7 Series begins by emptying your tank entirely. A motor that has been started means flushing the filter and lines through as well, and replacing the fuel filter if needed.
AdBlue that has gone into your diesel tank is the topic here. Disabling or taking out your car's AdBlue system is not part of it.
Pricing a fuel drain on the BMW 7 Series
There's no fixed price published on this page, since call-outs on one model can vary quite a lot. What affects it most is whether the 7 Series has been started or driven, and beyond that how much got in against the size of your tank, whether it was petrol or AdBlue, and where the vehicle is.
Ring with those details so we can let you know what this job will need.
Your tank questions on petrol in a diesel BMW 7 Series
Fuel tank capacity of the BMW 7 Series: how much does it hold?
It varies with the version, from 80 to 88 litres, and the table above has every one.
Does a bigger tank make petrol less of a problem?
That petrol is still there in a bigger tank, and still gets to your pump as soon as the motor runs, even though a few litres form less of the total. All of it is cleared with a drain, as long as your 7 Series is turned off.
How many diesel versions of the 7 Series do you cover?
Our figures include 9 diesel versions of the 7 Series, all set out in the table above, and so you can pick out yours there using the name printed on its badge.
Which fuels, other than diesel, would be wrong fuel in my BMW 7 Series?
Only diesel belongs in your diesel tank. Petrol of any grade, super unleaded too, is wrong fuel, and so is AdBlue, which belongs in a tank of its own.
Can you drain the BMW 7 Series wherever it is?
Yes, wherever it is. Sitting at home or still at the pumps, your car stays where it is and is not started, because we come to it.