Many diesel enthusiasts and vehicle owners are unaware that numerous regular-use additives on the market, typically sold in dosing bottles for each fill-up, are essentially glorified cetane improvers with minimal additional benefits. These products, typically packaged in 500ml to 1L bottles with recommended dosages of 1-2ml per litre of fuel, often fail to deliver the comprehensive fuel system benefits they promise.
This comprehensive analysis reveals the truth behind popular diesel additives, exposing industry practices and providing guidance on making informed choices for your diesel engine’s health and performance.
The Reality Behind Popular Diesel Additives
We recently received test results from arguably the most popular diesel additive in the UK. A household name with substantial brand history and recognition. This particular product, which comes in an attractive 500ml bottle, has gained significant popularity throughout Europe as well. This prompted a respected colleague to arrange a series of comprehensive tests, including FTIR Spectroscopy (to determine chemical composition) and titration (to measure detergent strength). A High-Frequency Reciprocating Rig (HFRR) test wasn’t necessary, as spectroscopy would reveal the type of detergent used.
The results confirmed what we already suspected. The product is essentially 2-Ethylhexyl Nitrate (2-EHN), a cetane improver, diluted in a solvent with a fatty acid lubricant, negligible detergent content, and an agent to improve the odor. In other words, it’s primarily a glorified cetane booster.
Key Test Results:
- HFRR Response: Poor at best, often nonexistent when combined with 2-EHN
- Titration Test: Just 2 drops (maintenance-strength products should register 15-20 drops)
- Primary Component: Diluted 2-EHN with minimal additional benefits
The HFRR response (which measures diesel lubricity) with this outdated and low-cost fatty acid technology is poor at best and often nonexistent when combined with 2-EHN. The titration test for detergent (measures amine strength) resulted in just 2 drops. For context, a maintenance-strength cleaning product should register at least 15-20 drops.
What You Should Look For in Diesel Fuel Additives
If you use diesel fuel additives or conditioners, it’s crucial to understand what you’re purchasing. Here are the key components to consider:
1. Fuel System Lubrication and Protection
If protecting your fuel system is important to you, verify what lubrication technology the product uses. Most additives on the market still use cheap mono fatty acid technology—we know this because we have FTIR analysis for many of them. This outdated technology is ineffective when combined with 2-EHN, as the cetane improver reduces the HFRR response.
Lubrication Technology Recommendations:
- Look for modern ester lubricants that aren’t negated by 2-EHN
- Request HFRR test results to verify effectiveness
- Avoid products relying solely on mono fatty acid technology
For optimal protection, look for products that use modern ester lubricants that aren’t negated by 2-EHN, and ask for HFRR test results to verify effectiveness.
2. Fuel System and Injector Cleaning
If you require cleaning performance, check what detergent technology is used and whether it’s present in sufficient dosage to provide continuous “keep clean” performance. Request test data to verify claims. Our analysis of many products on the market reveals that they contain very little to no detergent at all, despite marketing claims about cleaning capabilities.
Detergent Performance Indicators:
- Titration Test: Maintenance products should register 15-20 drops minimum
- Amine Content: Verify through FTIR spectroscopy analysis
- Dosage Strength: Ensure sufficient concentration for “keep clean” performance
3. Cetane and Combustion Improvement
For cetane improvement, pure 2-EHN (not diluted with cheap solvent) remains the most effective option. Combining it with a combustion catalyst will further enhance combustion efficiency and help clean the Diesel Particulate Filter (DPF).
- Pure 2-EHN: Most effective cetane improver without dilution
- Combustion Catalyst: Enhances efficiency and DPF cleaning
- Zero Solvent Fillers: 100% active ingredients for maximum value
The Market Reality
The market is flooded with brands selling thousands of bottles of diesel treatments daily that contain little more than diluted 2-EHN, a substandard lubricant, and some fragrance—yet they often receive glowing reviews. Why? Because 2-EHN will make a noticeable difference to most diesel engines, and manufacturers know this.
These companies focus on the one function that customers are most likely to notice: a more responsive engine from the cetane increase. It’s much harder for the average user to discern improved lubrication or effective cleaning. What’s particularly concerning is that these products typically contain less than £1.50 worth of chemicals in a 500ml bottle, despite their premium pricing.
Market Reality Facts:
- Most products contain less than £1.50 worth of chemicals per 500ml bottle
- Primary benefit comes from basic cetane improvement (2-EHN)
- Marketing focuses on easily noticeable engine responsiveness
- Lubrication and cleaning benefits are often minimal or nonexistent
Premium Alternatives: What Quality Looks Like
Understanding what quality diesel additives should contain helps distinguish between marketing hype and genuine value. Here are two examples of comprehensively formulated products that demonstrate what’s possible when cost isn’t the primary constraint.
Archoil AR6900-D Development
When we formulated AR6900-D for Archoil, our goal was to pack as much value as possible into the product using only high-end and proven components. The result includes:
Archoil AR6900-D Components:
- Ester Lubrication: Demonstrably improves lubricity in EN 590 diesel. The ester costs approximately four times more than traditional mono fatty acids.
- Comprehensive Detergent Package: Delivers the correct “keep clean” dosage for both older and modern vehicles, fully tested for cleaning performance and safety.
- Fuel Borne Catalyst: Helps improve combustion quality, particularly in the lower rev range, and assists with passive DPF regeneration.
- Pure 2-EHN Base: 100% active ingredients with zero solvent fillers.
This is a product we’re proud of as it genuinely offers quality and value. Fast forward a few years, and we faced a new challenge with Oilsyn Diesel Power DNA. The remit was similar to Archoil—to create a value-packed product—but with an important twist: make the best possible formulation regardless of cost and include additional carbon removal technology.
Oilsyn Diesel Power DNA
The Oilsyn Diesel Power DNA features:
Oilsyn Diesel Power DNA Components:
- Unique Ester Lubrication System: Not found in any other diesel product. This ester costs approximately eight times more than traditional mono fatty acids.
- Enhanced Detergent Package: Delivers optimal “keep clean” performance for both older and modern vehicles, fortified with polyether-amine to improve ongoing carbon removal and help neutralize carbon that might otherwise deposit in the intake, EGR, and valves.
- Stronger Fuel Borne Catalyst: Further improves combustion quality, particularly in the lower rev range, and enhances passive DPF regeneration.
- Pure 2-EHN Base: 100% active ingredients with zero solvent fillers.
Value Perspective:
The Oilsyn product offers so much value in a single bottle that it can be challenging to communicate its true worth to customers. To put it in perspective, a 50ml dose from a 1L bottle can contain more detergent performance and overall value than some competitors’ “high-strength” single bottle treatments that sell for £10+ per bottle.
The best advice we can offer is to pay closer attention to what you’re putting in your fuel tank and ensure it aligns with what you want from an additive. Whether you’re seeking improved performance, better fuel economy, reduced emissions, or extended component life, understanding the actual composition of diesel additives will help you make more informed decisions and potentially save money in the long run.
Key Decision Factors:
- Transparency: Look for products with clear information about their formulation
- Test Data: Seek products with supporting performance claims through verified testing
- Component Quality: Understand the difference between basic and premium ingredients
- Value Analysis: Consider cost per effective dose, not just bottle price
- Specific Needs: Match product capabilities to your engine’s requirements
Don’t be swayed by marketing claims alone – look for products with transparent information about their formulation and, ideally, test data to support their performance claims. Your diesel engine deserves better than diluted 2-EHN with minimal additional benefits.
Remember: An informed consumer is an empowered consumer. Take the time to understand what you’re buying, and your diesel engine will thank you with improved performance, longevity, and reliability.
