A piece of advice has long circulated in the Spanish automotive community: supposedly, adding a small amount of gasoline to the tank of a diesel car helps clean the injectors and restore the engineβs former flexibility. However, experts from the Real AutomΓ³vil Club de EspaΓ±a (RACE) have put an end to this debate, stressing that for modern diesels such an approach can lead to costly repairs and loss of warranty.
Old habits and new engines
The tradition of adding gasoline to diesel dates back to the era of simple naturally aspirated engines, when fuel systems were less sensitive to fuel quality. In cars produced before 2010, there really was a practice of adding a minimal amount of gasolineβno more than 1β2% of the tankβs volumeβto dissolve deposits in the injectors. But even then, overusing this method was not recommended: the risk of damaging the fuel system was always present.
With the advent of modern diesel engines, the situation has changed dramatically. New injection systems, especially common rail, require exceptionally clean and strictly specified fuel. Any deviation from the manufacturer’s recommendations, even a slight admixture of gasoline, can lead to injector failure, high-pressure pump damage, and lubrication problems. As RACE points out, for diesels produced after 2010, such an experiment is a direct path to serious breakdowns and bills running into thousands of euros.
Spanish market: diesels at risk
Spain has traditionally remained one of the largest markets for diesel vehicles in Europe, especially in the family and commercial segments. However, stricter environmental standards and the transition to new engine generations have made diesel operation more demanding in terms of fuel quality and service. In today’s environment, attempts to ‘clean’ the injection system using old methods are not only ineffective, but also dangerous for the equipment.
RACE emphasizes: even a single instance of gasoline entering the tank of a modern diesel can cause malfunctions in the fuel system, loss of power, and unstable engine operation. In the worst case, replacement of expensive injection system components may be required. For Spanish car owners, especially those who use diesels in urban areas or on long-distance routes, this means additional risks and expenses.
A safe alternative: only recommended products
Experts advise to completely avoid experiments with fuel and to use only those cleaning methods approved by the vehicle manufacturer. The market offers special diesel additives with detergent properties that safely remove deposits and keep injectors clean. Many premium diesel grades in Spain already contain such components, allowing the injection system to remain operational without risk to the engine.
For owners of petrol vehicles, the situation is less critical: injectors here become clogged less often due to the specifics of fuel combustion. Nevertheless, with high mileage and if performance deteriorates, it is also recommended to use branded additives or have preventive cleaning done at a service center.
Context: how maintenance approaches are changing
The shift in generations of diesel engines and tightening service standards in Spain require car owners to be more disciplined and attentive to manufacturersβ recommendations. Old advice that worked for engines of previous generations can now lead to serious problems. As with innovative hybrid suspensions recently discussed by russpain.com in the article on the unexpected comfort of the Panamera Turbo S E-Hybrid, new technologies require new approaches to operation and servicing.
For the Spanish market, where the share of diesels remains high, it is especially important to follow modern maintenance standards. Using uncertified cleaning methods can not only lead to breakdowns but also affect the carβs resale value. In the context of growing competition between hybrids, electric cars, and traditional diesels, proper maintenance becomes a key factor for long life and trouble-free operation.
