Wrong fuel in your Mercedes S420 CDI? Petrol in your Diesel Mercedes?

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Mercedes Fuel Drain


Putting Petrol in a Diesel Mercedes is a well-known error. And its solution is dependent upon several things. In the event that you want to find out what it is advisable to do about it then keep reading.
These are the most crucial factors to take into account when determining whether or not to have a fuel drain:

  1. How much Petrol did you put into the Mercedes, keeping in mind that the fuel capacity of your Mercedes S420 CDI is most likely approximately 90 litres?
    1. A small quantity of Petrol, something like 4.5 litres of Petrol in a Diesel S420 CDI will normally not necessarily be a huge problem. Experience has proven to us that an amount less than 4.5 litres (which is close to 5% of the fuel tank volume) is sometimes able to be adequately diluted by means of thoroughly topping the rest of the tank with Diesel.
      It's relatively rare to come across a car suffering from issues with less than 5% incorrect fuel contamination. Keep in mind that it is very uncommon - in no way impossible to encounter. You will discover a number of cars that don't stand any degree of contamination at all.
    2. Anywhere between 4.5 and 9 litres of Petrol in the Mercedes (5 to 10%) is a 50/50 scenario. Our experience has demonstrated that as many people get away with it as those who break down. Any time you're deciding on whether or not to risk it and just fill it up remember that it is the same thing as gambling everything on black - you've got a 50/50 chance of it being ok.
    3. Anything over 9 litres of Petrol in a Diesel S420 CDI should straightaway be drained as your probability of driving with that level of contamination is more than likely below one in fifty - extremely long odds.
  2. Put Petrol in a Diesel Mercedes and drove it: Have you seen any kind of performance concerns ever since putting the incorrect fuel in the S420 CDI? If that's the case, get it removed no matter the amount of Petrol or even the contamination ratio. Still running a vehicle that is already starting to suffer from the effect of fuel contamination will probably likely cause even more harm affecting the fuel system components.
  3. Are you looking for reassurance?
    In that case get it removed. Regardless of the contamination ratio, there is always some degree of danger in connection with operating a Diesel vehicle on fuel contaminated with Petrol. Possible final outcomes of driving a vehicle on the incorrect fuel can include the motor refusing to start, running unevenly, lack of power, degradation of the high-pressure pump, worn or clogged injectors, and so on. These are some of the most frequently seen Petrol in Diesel warning signs, and if you recognise any of them then stop and have it removed immediately.

Do not just get any untrained so-and-so to attend your vehicle. We are Mercedes specialists and possess the certification and working experience necessary to ensure you get back on the road with a minimum of hassle or worry.

Put Petrol in a Diesel Mercedes

By mistake put Petrol in a Diesel Mercedes? Or possibly even put contaminated fuel in your Mercedes S420 CDI?

Give us a call for Help & Recommendations

Call us and get honest recommendations and practical assistance for your specific circumstance

We show up and do a fuel drain

We would go to you to do the full fuel removal & purge there on scene

Once performed You Get Moving Again

As soon as we are done you will be able to get back on your way and get on with your trip

Wrong Fuel Drain Specialists

We are the primary wrong fuel drain authorities in the UK, offering national service, for Mercedes motorists especially. We mainly attend:

  • Unleaded petrol in a Diesel Auto
  • Diesel in an Unleaded Petrol Vehicle
  • AdBlue contamination
  • Water fuel contamination

We are Mercedes specialists and have successfully drained thousands of Diesel Mercedes vehicles. Regardless of whether it is at the roadside, on a petrol station forecourt, or even at your house, we can get you on the road once again.

The Procedure

The process of draining Petrol from a Diesel car is essentially similar for the majority of motor vehicles. Of course it may vary a little as every manufacturer has their own different fuel system. However it still basically adheres to the below principles:

Petrol in Diesel Mercedes

Fuel Drain

Empty the Fuel Tank

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Wrong Fuel Drain Mercedes

System Flush

Clean out the fuel lines & pumps

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Petrol in Diesel Drain Mercedes

Vehicle Restart

Get the car up and running again

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Petrol in Diesel FAQs

When someone has put Petrol in a Diesel car they have a few very common questions. So we have compiled a list of the most Frequently Asked Questions for you

I put Petrol in a Diesel car and drove it. What do I do?


Turn off the car as soon as possible and call us. Continuing to run a vehicle on the wrong fuel can potentially damage it. We will be able to give you advice and assistance based on your circumstances

Will driving a Diesel car on Petrol cause damage to it?


It can. However, if the problem is caught and remedied quickly the risks will be minimal. Of the 1,500 vehicles we attend every month, less than 0.5% have suffered and substantial damage requiring parts replacement.

How much Petrol can I get away with in a Diesel car?


The safe answer is none. However you might be able to get away with a very low contamination ratio. That being said, we always highly recommend draining anything over a 5% contamination ratio asap.

I know about petrol in diesel, but what about Super Unleaded?


Putting Super Unleaded, or Shell V-Power, BP Ultimate Unleaded, etc, will have the exact same effect as putting regular unleaded petrol in your diesel car and will need to be drained out and flushed.

Will getting you to do a fuel drain void my warranty?


No! The EU Block Exemption Regulations clearly state that "the work can be carried out by as long as that garage uses manufacturer approved parts and correctly follows the manufacturer's service schedule."

Can I top it up with Diesel and add some 2-stroke oil?


This might work on some vehicles in some cases, but in the majority on instances it won't and you risk damaging the Lambda sensors as well as fuel pump and injectors, just as a regular misfuel.

Call us

In the event that you have any questions or want assistance please Contact Us!
We can get you moving once again.

24/7 Mercedes Helpline

0333 366 0103

Our Business Office

Fuel Fixer Ltd, Linx House, 147 London Road, East Grinstead, RH19 1ET

Weekdays: 9am to 5pm

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