Although 150,000 people every year, put the wrong fuel into their vehicles in the UK alone, the wrong fuel emergency industry is still one that very few people have a good level of knowledge about. In fact, unless you’ve been personally affected or know someone who has, very few people even know that a mobile fuel drain exists. Unfortunately, this means that those affected are often misled by others who claim to have a little knowledge or they may read something about what to do if you’ve put in the wrong fuel, on the internet. Our engineers are often dealing with customers who have taken bad advice from someone who appears to have a little knowledge of the situation and sometimes from those in the auto industry who should know better. At this time of year, there is one piece of bad advice that seems to do the rounds more than usual and that is as follows:
“Diesel can turn a little sludgy in really cold weather, so if you’re having trouble starting your diesel vehicle or it’s running rough, add some petrol to it to loosen it up a bit”
If you’re contemplating doing this with your diesel vehicle, Stop right there! This is actually terrible advice even though it might sound logical to some. It makes more sense to keep your diesel vehicle fuel tank topped up as full as you can or to try and park it in a garage or a sheltered location. Once the vehicle has warmed up, it should run fine so try allowing yourself some time to do that. Let the vehicle engine run for a short while before you go anywhere.
Why shouldn’t you add a little petrol to diesel fuel?
As we have covered several times in similar articles, petrol is a solvent and does not have the lubricating properties of diesel. Petrol vehicle and diesel vehicle engines have very different fuel systems which work in very different ways. The diesel vehicle fuel system relies upon the lubrication of the diesel passing through it to ensure that there is no friction where metal parts come into contact which each other. If you add petrol to the diesel fuel then this will indeed “loosen it up a bit”, unfortunately this means that the lubrication of the diesel vehicle fuel system is compromised and you start to get a friction build up between metal parts which can cause damage to them. This may result in the requirement to change fuel system parts such as filters and pumps, but there is also another far more serious consequence. The friction between moving metal parts can result in tiny metal particles, called swarf, getting into the diesel fuel as it passes through the fuel system as the metal parts begin to disintegrate. If this swarf makes it as far as the fuel injectors, then you may be in serious trouble. Blocked injectors are very difficult to remedy and if the injector is damaged then it will need to be replaced. Very often, this is an extremely expensive job, especially if you drive a premium vehicle such as a BMW or Mercedes. Even a regular family saloon would be an expensive fix.
One of our engineers recently came across a situation where the customer’s vehicle was running badly and they were requesting advice. He turned up at the customer’s home to take a look at the vehicle and learned that the vehicle had been running with a little petrol in it’s diesel tank for a while because the customer had been advised by a friends that this makes them run better! In this case the diesel injectors were damaged and one was completely blocked and beyond salvage. The vehicle was a BMW X5. The repair bill was frightening!
Always consult a wrong fuel expert before following any dubious advice that you see on the internet. Even if it comes from a trusted friend, our experts have many years of experience in this field and will usually have better advice for you.