In Italy the phenomenon of fuel “cut” at distributors has recently returned to the news and the numbers explain why: between March 1st and July 31st 2026, the Guardia di Finanza concluded 1,371 interventions regarding excise duties on energy products (petrol and diesel), with 265 people reported and over 20 thousand tons of product seized. In Rome, in a plan of random checks, approximately one distributor in five was found to be irregular, with more than 10 tonnes of non-compliant fuel blocked in the capital alone. In the meantime, many workshop mechanics have reported an unprecedented boom in engines damaged by adulterated petrol and diesel. What makes the moment favorable for fraud are the prices: the high costs at the distributors make it more profitable to “stretch” the fuel with cheaper substances.
But what does “watered down fuel” mean chemically (spoiler: it’s not water) and how do you find out before you damage your engine? We talked about it with Fabrizio Apruzzesehead of the chemical laboratory in Rome of theCustoms and Monopolies Agency (ADM)the body that in Italy supervises the quality of petrol and diesel and the collection of excise duties (the manufacturing taxes on these products).
How petrol and diesel are “watered down” and what happens: designer fuel
To fuels no water is addedthis is a media simplification. “If there was water inside the volume of petrol and diesel the engine wouldn’t even start.” It happens that in some cases there is a small quantity of water in the supplies, but this is due to the negligence of those who manage transport and distribution.
«Water is naturally present in the atmosphere: if the external temperature is high due to the heat and the tank is kept cooler to avoid evaporation of the product, some condensation forms. However, this does not mix with petrol because it is heavier and therefore remains at the bottom and normally all tanks have taps at the base that allow it to be bled”.
To be used to increase the volume of the product are quite organic solvents, waste materials from industrial processesor, increasingly, the so-called “designer fuel” produced in the laboratory. As Apruzzese explains to us, the Customs and Monopolies Agency is involved in controls on fuels as they are products subject to excise duties, which they collect. The agency follows the entire diesel and petrol supply chain starting from the oil refineries and up to the distributor where the consumer fills up.
The moment in which the fuel arrives at the distributor is the most critical, because it is the most difficult to control, and this is where fraud can occur. How does it happen? Increasing the volume of petrol and diesel through the addition of non-excised productand therefore cheaper. «For about a year – explains Apruzzese – we have noticed an increase in designer fuel, i.e. fuel made in the laboratory, a product very similar to diesel which however, for fiscal and customs purposes, is classified as lubricating oil, and is therefore not subject to excise duty». The lack of excise duties not only makes it cheaper, but exempts it from controls and transport constraints, allowing it to travel as easily as any other non-subject good.
How the Customs and Monopolies Agency controls work in Italy
Since 2017 the Customs and Monopolies Agency has inaugurated the use of mobile laboratories on four wheels, which allow checks to be carried out close to the distributors and at speed: it takes around half an hour to analyze a single sample. Once the samples had to be sent to the laboratories where subsequent and more in-depth analyzes are now carried out, extending the timescales and not allowing the seizure seals to be affixed immediately, leaving any time to replace the product and cover up the fraud.
The mobile laboratory allows you to immediately check for adulterations and arrange for immediate seizure. «The vehicle has an internal power generator which allows the laboratory to be autonomous. While the checks of the documentary part continue at the distributor, also in collaboration with the Guardia di Finanza, with the loading and unloading registers, which also takes a few hours, in the meantime we are able to ascertain any irregularities”.
During the analyses, he comes simulated distillation through an instrument that heats the sample: «we often find products that have a wide distillation spectrum, with substances that come to boil before the diesel, and others after, varying the flash point of the diesel and suggesting to us that the product is counterfeit». The legal temperature limit at which diesel vapors catch fire is set at 55 degrees: if a product that catches fire at lower temperatures is added, it is easy to realize this by analyzing the sample.
The gas chromatograph, then, it returns a profile in the form of peaks: if they are regular and homogeneous it is likely that the fuel is intact, while if anomalous ones appear it means that the product is mixed. In the fixed laboratories, more in-depth analyzes are carried out which allow the complete classification of the product in the following hours.
How to protect yourself: the symptoms of impure diesel fuel and what to do in the event of fuel faults
How can I understand when refueling if the fuel is cut? “I can’t,” explains Apruzzese. In case of counterfeiting of petrol and dieselthe engine may fail and stop after a few kilometers of walking. In that case, the only figure who can ascertain the causes and repair the damage is the mechanic in the workshop.
As drivers, we can realize that something is wrong if the engine misfires and seems to go in spurts, rather than smoothly or suddenly loses power. This, explains Apruzzese, «could be the first sign. If it happens after refueling at a specific petrol station, we can start to understand that something might be wrong with the fuel.” In general, we may also experience difficulties in starting and muttering when accelerating. In some cases, the water in the fuel filter warning light may come on on the dashboard.
Apruzzese invites you to prudence and common sense when we choose where to refuel: «The general purchasing rules apply: if I buy in a more refined and clean distributor, where frequent maintenance by the manager is visible, I can expect that the product will also be more reliable; compared to very old and neglected distributors, however, I recommend greater caution”.
What if the engine is damaged by refueling? We can report it, with complete documentation from the workshop, to the Customs and Financial Police Agency.
