Quick Answer
Excessive cetane improver use (over 0.5% by volume or manufacturer recommendations) can cause injector deposits, seal degradation, and emission system issues. Over-treatment may reduce fuel economy and create combustion timing problems. Stick to recommended dosages of 1-5ml per litre.
Expanded Answer (Simplified)
While cetane improvers provide significant benefits, using too much can actually harm your engine and fuel system. The general rule is never to exceed 0.5% by volume of your fuel tank capacity, which typically translates to no more than 5ml per litre of diesel fuel.
Overuse can lead to several problems including fuel injector deposits, degradation of rubber seals and gaskets in your fuel system, and interference with emission control systems. You might also notice reduced fuel economy and changes in engine performance that indicate combustion timing issues.
The key is finding the right balance – enough to improve ignition quality and performance, but not so much that you create new problems. Most engines show optimal results with 2-3ml per litre, and there’s rarely any benefit to exceeding this amount.
Expanded Answer (Technical)
Excessive cetane improver application can cause multiple system complications through chemical overconcentration, material compatibility issues, and combustion parameter modification beyond optimal ranges. Understanding overdose mechanisms is critical for preventing costly system damage.
Chemical Overconcentration Effects
Cetane improvers contain nitrate-based compounds that can cause adverse effects when concentration limits are exceeded, affecting fuel stability, combustion characteristics, and system component integrity.
- Fuel system deposits: Excessive nitrate compounds can form deposits in injectors and fuel lines
- Oxidation acceleration: High concentrations may increase fuel oxidation rates and gum formation
- Thermal stability reduction: Overconcentration can reduce fuel thermal stability at high temperatures
- Phase separation risks: Excessive additive levels may cause fuel component separation
Material Compatibility Limitations
Fuel system materials have specific compatibility limits with cetane improver chemicals. Exceeding these limits can cause degradation of seals, gaskets, and other fuel system components.
- Elastomer degradation: Nitrate compounds can cause swelling or hardening of rubber seals
- Metal corrosion: High concentrations may accelerate corrosion of fuel system metals
- Plastic compatibility: Some fuel system plastics may be affected by excessive additive levels
- Coating damage: Fuel tank coatings and linings may be compromised by overconcentration
Combustion System Impacts
Excessive cetane improvement can alter combustion timing and characteristics beyond optimal parameters, potentially causing performance issues and increased emissions.
- Ignition timing advancement: Excessive cetane can cause premature ignition and knock
- Combustion pressure changes: Altered burn rates may affect peak cylinder pressures
- Emission system effects: Changes in combustion may affect aftertreatment system performance
- Engine calibration mismatch: Modern engines are calibrated for specific fuel characteristics
Safe Usage Guidelines
Preventing cetane improver overdose requires adherence to established concentration limits and systematic monitoring of system performance to detect early signs of overtreatment.