It’s the Wrong Fuel!


Putting the wrong fuel into your tank is something that none of us would ever think we could do, yet each day, in the UK alone, as many as 150,000 do it every year. This number is perhaps a small proportion when we look at the number of vehicles that are in regular use across the UK but significant enough for organisations like the AAA and the RAC to have dedicated teams on standby to help out those who have done it.

In the UK, the hose to the petrol tank is green while for diesel it is black, and it’s good to use this as a visual check, although in the US it’s the other way around – black for petrol and green for diesel! Furthermore, the nozzle to the diesel gun should usually be too big to fit into the petrol aperture on your car. That may be the theory, but it is not always the case! So, two key reminders cannot be trusted. The only way is to pay attention at the time of selection at the pump. Now, having got this far through the article, think about checking your insurance policy as you may already have cover. It’s worth a look, and if not, what will it cost to get it?

One can safely assume that before filling up, the ignition is off and the key is either out or away from the car and the chances of it being inadvertently switched on remotely. If you are unfortunate enough to do this, do nothing to the car. Don’t touch the ignition because once it goes on, whatever is in the tank or the pipes will be under pressure and pumped around. The system needs to be totally isolated and the fuel retained exactly where it is. Even a second or two will do some damage.

This is the time when you call the motoring organisation of your choice, primarily AAA or RAC. The garage you are in may offer to help or now someone locally who can help. Turn down this advice unless you are confident in the ability of the person in question and go for a recognised name, like that of a reputable motoring organisation to ensure fair treatment.

Of the two options, petrol going into the diesel tank is the more precarious of the two, while diesel in the petrol tank is less serious and something I managed to do many years ago. However, today cars are governed more by electronics than mechanicals, and any such mistake must be dealt with immediately. I have deliberately not gone i to technical details here as the purpose of the article is purely to give advice on what to do if it happens to you. So, leave the car where it is, take out the key so that no one else can move it, and call for help.

What has made me fearful of making such a mistake is that during a recent trip to the US I grabbed the nozzle with the green tube to fill up my hire car. The forecourt like many in the US was grubby and so too was the handle of the pistol, and this alerted me to the fact that something was different. I didn’t get as far as trying to insert the nozzle in to the filler pipe, but it was close.

Also, as an aside, it seems that motor home and caravan owners regularly fill their water tanks with diesel or petrol, and although the vehicle can still be driven or moved, it’s useless for what it was designed for. A few months ago, I was in a hurry to fill my boat with diesel. Time was short, the pontoon was busy, the dock master was keen to move vessels on and off, and I needed three hundred litres or so of fuel. A couple of minutes on and I called to my companion and asked how the gauge was moving. It wasn’t moving. Perhaps she was watching the wrong gauge? No, the reply came back, but perhaps I was filling the wrong tank! My unrepeatable response initiated a call from the dockmaster that I would have to pay for the 108 litres I had just taken. I now had 275 litres of diesel and water in my water tank. Of course, before moving on, I had to fill up the fuel tanks with the 300 litres I wanted initially. Fortunately, as I happened to be in Guernsey, it wasn’t so bad as fuel there is virtually duty free.

Boats are made of GRP – plastic – and parts are welded together around components. Therefore, removing a water tank running across much of the width of the boat would have meant cutting the boat open and this I understood was the only option. For those who have caravans and motor homes, the issue is not so serious, although for everyone with fuel in water, the same procedure applies to flush out the system.

My first challenge was to get rid of the stuff and clean out my tanks. My water pump is usually left on to maintain pressure in the system, as in any domestic water supply, which meant that as the diesel was flowing in, it was being evenly distributed across through pipes. By chance, I managed to find someone who was able to empty the tank within eighteen hours of it being filled.

I headed back to England to meet someone who specialised in dealing with water in diesel – completely different to what I needed, but at least a start. A few phone calls later, we realised that technology had moved on and perhaps the tank did not need to be replaced. The answer was a product called “Bio Magic”.  We made contact with the supplier and bottles were delivered to the depot the following morning.

Designed it would seem for the motor home/caravan owner, there seemed no reason why it couldn’t be used in a boat. First task, with the tank empty, was to flush it out with washing up liquid and methylated spirits. Sounded very simple, but what came out later showed little evidence of diesel. The next task was to fill the tank with a mix of Bio Magic and warm water and to leave it for 24 hours. This we did, and when we flushed through the next day, evidence of diesel was further reduced.

Unfortunately, the mistake made was to flush out using mixer taps on neutral as opposed to hot and then cold. Therefore, a small amount of diesel was left in the system and because we had not run the process strictly to the instructions, we had actually moved the diesel further into the system. Once realised and the process run again from the beginning, we managed to eradicate all traces of diesel from the system, and since then I have had numerous showers in the boat without any diesel glistening.

This article may not be relevant to everyone, but its purpose is to demonstrate that sometimes there is an easier solution to a problem that appears insurmountable, such as fuel in the wrong tank, as this latter one did to me and my sailing friends.

John Hall

John joined Alfa Energy in 2013 as Chairman, where his specific interest is the development of the company’s profile in the areas in which it primarily operates - across the EU and the US. He is Fellow of the Energy Institute, a Member of the Parliamentary Group for Energy Studies, an Associate Member of the Chartered Institute of Purchasing and Supply, and a Member of the Market Research Society. He began his long career in the industry when he set up John Hall Associates in 1973, a company which merged with Energy Quote in 2009 and currently trades as Energy Quote JHA.