4x4 PROFESSOR
You explicitly told the petrol attendant to fill up with diesel, but then he went and topped up your tank with petrol. What should you do now?
This is exactly what happened to François Haasbroek five years ago. François is a journalist at our sister magazine go! and we still tease him about not knowing the difference between petrol and diesel, despite his insistence that it wasn’t his fault.
Before we hear what François did about his dilemma, we first have to talk about the
differences between these two types of fuel, and while we’re at it we should also discuss using 500 ppm diesel in an engine approved for 50 ppm.
Petrol and diesel
These fuels are distilled in the same way, and it works as follows: crude oil is heated and water is mixed in it – the resulting steam makes it easier to desalinate the oil. Words Cyril Klopper Illustrations Dominic Wienand This watery “clean” crude oil is then further heated to temperatures of around 600 °C until it is converted into a superheated gas that’s pumped to a distillation tower. The tower has several chambers through which hot gas rises or falls.
The gas that evaporates at the top of the tower has by now cooled to around 20 °C and is now volatile enough to be used as LPG – that’s the gas used by your Cadac gas cooker, the one with which you cook bacon and eggs next to Satara’s fence.
In the upper quarter of the distillation tower – where the temperature drops to an average of 150 °C – a light liquid is pumped out, which is converted by further processes into naphtha, kerosene and petrol. In the middle of the distillation tower, the temperature is about 300 ° C and
it is here that they tap a heavier liquid from the tower, which will later be converted to diesel.
In the upper layer of the lower quarter of the tank, oils are tapped (engine oil or heavy fuel oil) that may be used as fuel for, among other things, cargo ships, and right at the bottom lies tar with which highways are built.
South African fuel manufacturer Sasol does things slightly differently: instead of crude oil being heated and desalinated before being pumped to a distillation tower, coal is superheated in a methyl gas furnace until it becomes a gas – called syngas – that is further treated with the FischerTropsch process. The general principle of the Fischer-Tropsch process isn’t a state secret, but you won’t find its finer workings on Wikipedia. With this process, Sasol can not only distill fuel from coal, but also produce polypropylene, acrylic, butane, ethyl and exotic chemicals such as 1-Hexene used in perfumes and food flavourings.
Sasol does not only rely on coal for its products. Its state-of-the-art Natref oil refinery in Sasolburg is known for its superior fuel distilled from medium weight oil. This oil delivers a fuel that is 70 % cleaner than coastal refineries can produce from regular heavy crude oil.
50 ppm or 500 ppm?
Mike Reitz, a reader from the Strand, asked us whether he can put 500 ppm diesel into his 2015 Ford Ranger XLS 3.2 4x4 automatic as 50 ppm diesel isn’t available everywhere on his travels. Like many other motorists, Mike is concerned that using the “dirtier” diesel could cause short- or long-term damage to an engine that was designed to use 50 ppm diesel. The good news is that you can use 500 ppm diesel without the engine suffering, but only in the short term.
The abbreviation ppm is for “parts per million” and indicates the number of sulphur particles, which means that 500 ppm diesel contains 10 times more sulphur than 50 ppm diesel. Sulphur is a natural element of crude oil, and heavy fuel oil used by cargo ships can contain up to 33 000 ppm of sulphur.
Mike is concerned that using dirtier diesel could cause damage to an engine that was designed to use 50 ppm diesel
When sulphur comes into contact with nickel (the metal layer on the inside of your engine) it forms a type of lubricant that protects your engine from wear and tear.
If the sulphur content in
diesel is reduced, the fuel manufacturer needs to replace the natural lubricant with something else.
So why should the sulphur content be lowered? Diesel is a big offender in terms of pollution and the particles emitted by your truck’s exhaust pipe are cancerous. Health organisations have convinced First World governments to ban the sale of engines that release high levels of nitric oxide and particles.
Diesel engines nowadays need to use catalysts and other filters to remove the toxic substances from the exhaust gases. Sulphur damages these filters, which is why its level needs to be reduced.
Engines designed to work without sulphur (or with very little of it) can also be overwhelmed by high levels of sulphur, which results in that sulphur breaking down the engine oil’s stickiness, which in turn leads to greater wear and tear.
In a nutshell, you simply need to know the following: 500 ppm diesel will eventually consume your engine’s catalyst and put humanity at risk of cancer, and your engine oil will have to be replaced every 10 000 km rather than every 20 000 km, all while poisoning earth.
If you fill up with 500 ppm every now and then, nothing will happen. If, however, you use 500 ppm every day, you’re showing a proverbial middle finger at everyone and everything around you.
FRANÇOIS’ MISHAP
In 2014, I travelled through Namaqualand and the West Coast with a Hyundai iX35 and stopped at Garies for fuel. The Hyundai’s tank was still half full, but because that part of the West Coast doesn’t have many filling stations, I decided to rather fill up.
The attendant must have heard wrong because he put petrol into the half-full diesel tank, and I left – not suspecting a thing. The petrol must have been resting on top of the more dense diesel, because I drove without incident to Hondeklip Bay, about 100 km from Garies.
The next day when I tried to start the car at the fishing village harbour, I suddenly realised there was a problem. The engine shook and stuttered, but at least it was still going. At first, I didn’t know why the engine was protesting, but I got an inkling when I saw blue smoke and smelt petrol vapours.
I checked the receipt and saw that I had paid for petrol instead of diesel. There is no garage at Hondeklip Bay, but two fishermen came up to me and offered to help.
When they heard it was petrol in the diesel tank, they lifted the Hyundai’s right-hand side with a jack, then pushed a piece of garden hose through the fuel filler towards the left right to the lowest section of the tank and sucked it empty.
As a reward for their help, I donated the approximately 30 ℓ polluted petrol for their boat. I bought a can of diesel from a guy selling fuel in the town and it was enough to get to Kleinsee where I could fill the tank – this time I made sure they were using diesel.
I travelled hundreds of kilometres without incident on that trip and, as far as I know, that Hyundai is still running today.
Did François do the right thing?
We talked to a mechanic and he doesn’t believe there would be lasting damage. He does think François should also have drained the fuel pump, although
that little bit of petrol in a diesel engine wouldn’t hurt.
If, however, François had decided to drive until the tank was empty of petrol, chances would have been good that the cylinders would be damaged, and then the engine would have had to be rebuilt.
If the situation was reversed and François used diesel in a petrol engine, our competent mechanic reckons there would have been even less to be worried about.
The worst thing that could happen is that you have to replace the petrol filters, oil and some sensors, but the reality is that a diesel pump’s spout won’t even fit in the fuel filler of a petrol vehicle.
According to the fuel manufacturer BP, there’s no reason to panic if you receive the wrong type of fuel. The probability of engine damage is relatively low, according to BP, provided you remove the wrong fuel as soon as possible.
However, the AA and the insurance company MiWay’s websites differ on this and argue that mechanical catastrophe and financial loss are inevitable.
The British television program Fifth Gear performed an experiment in which they put
5 ℓ of diesel into a petrol car.
They went for a ride and the car stuttered and swallowed but kept driving. (They should have used Vin Diesel, that would have been a spectacle! – Ed) After the ride, they filled the tank with petrol and the car returned to normal. Mechanics could find nothing wrong; even the catalyst was 100 %.
Fifth Gear’s guys then put 5 ℓ of petrol into a diesel-powered car. The car at first drove well, but eventually also started to stutter and smoke.
After filling the tank with diesel, the car returned to normal again, without damage.
Incidentally, the cars tested by Fifth Gear were from the nineties and modern petrol and diesel engines may not be as tough as the engines from those days.