Is There Harm in Adding Too Much Fuel Additive?

[AnthonyRose]

Adding too much fuel additive can be harmful. Fuel additives are auxiliary fuel supplements, and long-term excessive use can increase carbon deposits in the combustion chamber, lead to engine knocking or detonation, and worsen vehicle exhaust emissions. Therefore, it's important to pay attention to the quality of the fuel additive when using it. The role of fuel additives is to clean the fuel system. They are added to the fuel tank when refueling and clean carbon deposits during vehicle operation, thereby improving gasoline atomization and ensuring more complete combustion. Fuel additives are primarily used to compensate for fuel quality defects and incidentally provide some cleaning and protection for the fuel system and engine cylinders. The working principle of fuel additives is to create micro-explosions in the combustion chamber, causing secondary atomization of the fuel, promoting complete combustion, enhancing engine power, improving thermal efficiency, and reducing emissions.

[ParkerLee]

Fuel additives are definitely not something you can just pour in like a drink. Once I accidentally added half a bottle too much, and the car clearly didn't run right. Overdosing leads to increased combustion residues, making carbon buildup worse than not using it at all. Chemical residues can also corrode fuel lines—I've personally seen cases where the sealing rings of old cars' fuel injectors were melted. Especially those containing polyetheramine, excessive amounts can form gel-like substances that clog fuel injectors. The scariest part is the catalytic converter—metal additives can sinter and completely ruin this component worth thousands. Cars meeting China VI emissions standards need extra caution, as chemical buildup can clog the particulate filter, disabling its regeneration function. Long-term overdosing can even poison the oxygen sensors, guaranteeing failed emissions tests. Remember the ratio marked on the bottle—usually one bottle per 50-liter fuel tank. When in doubt, less is more.

[SanEli]

My auto repair shop has seen too many cases of problems caused by fuel additives. The most typical one is excessive detergent causing piston ring sticking, leading to the engine burning oil. Last time, a Mercedes had white smoke on cold start, and upon disassembling the engine, we found that excessive additives had corroded the valve stem seals. Chemical residues can also alter fuel atomization, causing the tachometer to fluctuate wildly at idle like it's dancing. I recommend diluting the excess immediately by mixing in higher-octane gasoline and running two full tanks to flush it out. Never mix different brands of additives—last time a customer added two types simultaneously, and crystalline particles directly precipitated in the fuel line. In fact, using fuel additives in the standard amount periodically can indeed clean carbon deposits, but excessive use is like destroying your car, especially for older vehicles—caution is crucial.

[AugustDella]

The hazards of excessive fuel additives are real. First, deposits from metal salt additives can scratch cylinder walls – I found longitudinal scratches during my engine overhaul. Second, excessive detergents cause large chunks of gum deposits to break off. Last month, a friend's car had its fuel filter completely clogged this way. Third, overdose of octane boosters interferes with ECU's knock detection, causing ignition timing disorder. After overusing additives once during highway driving, my check engine light suddenly came on. The repair shop's diagnostic showed long-term fuel trim exceeding 20% limit (indicating over-rich mixture). The solution required disconnecting the battery to reset ECU, followed by three tanks of fuel with standard additive dosage to normalize.