Diesel Additive National Standard (GB) Testing: Methods, Testing Items and Compliance Guide

Diesel additive national standard (GB) testing verifies that fuel additives, including detergents, cetane improvers, lubricity agents and cold-flow improvers, meet Chinese national and industry standard requirements for composition, physicochemical properties and performance. Conducted by accredited third-party laboratories, this testing ensures that treated diesel fuel remains fully compliant with GB 19147 and related diesel fuel specifications. This guide explains the sample types, testing items, methods and applications involved in a complete compliance evaluation.

Technical Overview

Diesel additives are chemical formulations dosed into diesel fuel at low treat rates to enhance performance, protect engines and maintain fuel quality. Major functional categories include detergent and dispersant packages for injector and combustion chamber deposit control, cetane number improvers, lubricity additives for fuel injection equipment, cold-flow improvers and wax anti-settling agents, antioxidants, corrosion inhibitors, metal deactivators, demulsifiers and antifoam agents.

National standard (GB) testing for diesel additives serves two purposes. First, it characterizes the additive concentrate itself, confirming identity, purity, elemental composition and physicochemical properties such as density, viscosity, flash point and ash content. Second, it evaluates the additive at the manufacturer's recommended treat rate in a base diesel, demonstrating both performance efficacy and a "no-harm" result, meaning the treated fuel still complies with all limits of the national diesel fuel specification GB 19147 (or GB 25199 for B5 biodiesel blends). Testing is typically performed by accredited third-party laboratories with CNAS or CMA accreditation, using samples taken in accordance with GB/T 4756.

Testing Samples

Neat Additive Concentrates

The product as supplied by the manufacturer, in its original sealed packaging, is tested for appearance, physicochemical constants, active component content and trace contaminants such as sulfur, nitrogen and metals.

Treated Diesel Fuel Blends

Base diesel conforming to GB 19147 is dosed with the additive at the minimum recommended treat rate to produce test blends for no-harm verification and performance evaluation.

Untreated Base Fuel (Reference Sample)

The same base diesel without additive is tested in parallel so that performance improvements, such as lubricity enhancement or cold filter plugging point depression, can be quantified as measured differences.

Biodiesel-Containing Blends

For additives intended for B5 fuel, blends prepared with fatty acid methyl ester (FAME) meeting GB/T 20828 are evaluated against the GB 25199 specification, including FAME content verification.

Retention and Dispute Samples

Duplicate sealed samples are retained for market surveillance, tender documentation, customs clearance and contractual dispute resolution.

Testing Items

For the additive concentrate, typical testing items include:

• Appearance, color and homogeneity
• Density at 20 °C
• Kinematic viscosity at 40 °C
• Flash point (closed cup)
• Pour point and cold stability
• Moisture content and mechanical impurities
• Ash and sulfated ash
• Acid number or base number
• Total sulfur and total nitrogen content
• Metal content (Fe, Cu, Zn, Ca, Mg, Na, P and others)
• Copper strip corrosion tendency
• Storage stability and compatibility with fuel system materials

For the treated diesel, the no-harm verification suite covers the full GB 19147 parameter list, including:

• Oxidation stability (total insolubles)
• Sulfur content
• Flash point (closed cup)
• Cetane number and calculated cetane index
• Distillation curve, including the 95% recovery temperature
• Density and kinematic viscosity
• Lubricity (wear scar diameter by high-frequency reciprocating rig)
• Cold filter plugging point and pour point
• Water and sediment, ash and copper strip corrosion
• Color and visual appearance

Performance efficacy items, measured as improvements relative to the untreated base fuel, include injector nozzle cleanliness and deposit control, cetane number increase, wear scar diameter reduction, cold filter plugging point depression, foam suppression and oxidation stability enhancement.

Testing Methods

Physicochemical Characterization of the Additive

Density is determined by GB/T 1884 and GB/T 1885 or SH/T 0604, kinematic viscosity by GB/T 265, flash point by GB/T 261 (closed cup) or GB/T 3536, and pour point by GB/T 3535. Water is measured by GB/T 260, mechanical impurities by GB/T 511, ash by GB/T 508 and sulfated ash for additive-containing products by GB/T 2433. Acidity is evaluated by GB/T 264 or potentiometric titration per GB/T 7304.

Elemental and Compositional Analysis

Sulfur in the additive and treated fuel is measured by GB/T 11140 (X-ray fluorescence) or SH/T 0689 (ultraviolet fluorescence, equivalent to ASTM D5453), with GB/T 17040 as an alternative energy-dispersive method. Nitrogen is determined by oxidative combustion chemiluminescence, and trace metals are quantified by inductively coupled plasma optical emission spectrometry or atomic absorption spectroscopy. FAME content in biodiesel blends is confirmed by infrared spectrometry per GB/T 23801.

Fuel Quality Verification (No-Harm Testing)

The treated blend is tested against the complete GB 19147 or GB 25199 limit table. Cetane number is determined by GB/T 386 with cetane index calculated per GB/T 11139, distillation by GB/T 6536, oxidation stability by SH/T 0175, cold filter plugging point by SH/T 0248, water and sediment by GB/T 6533, copper strip corrosion by GB/T 5096, color by GB/T 6540, and lubricity by SH/T 0765 (equivalent to ISO 12156-1 and ASTM D6079). Comparable ASTM methods such as D86, D445, D93, D5453 and D6079 are used when reports for international clients are required.

Performance Evaluation

Functional performance is demonstrated through comparative bench and rig testing: nozzle cleanliness and deposit control using standardized injector fouling rig or engine-based detergent procedures, cetane improvement by comparing GB/T 386 results on treated and base fuels, lubricity improvement from paired HFRR wear scar data, and low-temperature performance from paired CFPP and pour point data. Foam suppression and demulsification are assessed with standard agitation and separation bench procedures.

Sampling and Quality Assurance

All samples are drawn and handled according to GB/T 4756 to ensure representativeness. Accredited laboratories operate under documented quality systems, use certified reference materials and report measurement uncertainty where required, issuing test reports that are valid for regulatory submission, tendering and trade.

Applications

GB standard testing for diesel additives supports stakeholders across the fuel and additive supply chain:

• Additive manufacturers performing product development, factory quality control and national compliance certification of new formulations
• Refineries, fuel blenders and distributors verifying that finished treated diesel meets GB 19147 before release to market
• Importers and exporters requiring recognized test reports for customs clearance and cross-border trade documentation
• Bidding and tender submissions where independent proof of additive performance is required
• Market surveillance authorities conducting supervision sampling and spot checks of retail diesel and additive products
• Engine and vehicle OEMs evaluating additive effects on injection equipment durability and aftertreatment compatibility
• Contract dispute resolution and insurance claims supported by retained-sample analysis in accredited third-party laboratories

FAQ

What treat rate should be used for testing?

The additive should be tested at the manufacturer's declared minimum recommended treat rate, which typically ranges from about 50 ppm to 1000 ppm depending on the product type. The treat rate must be documented in the test report so results can be traced to real-world use conditions.

Which standards govern diesel additive testing?

There is no single universal additive specification; testing combines characterization of the concentrate with no-harm verification of the treated fuel against GB 19147 (diesel) or GB 25199 (B5). Related references include GB/T 20828 for biodiesel blend stock, GB 29518 for diesel exhaust fluid used in SCR systems, GB 19592 for fuel detergent frameworks, and the specific GB/T and SH/T test methods listed above.

How much sample is required?

Typical requirements are 0.5 to 1 liter of additive concentrate and 20 to 50 liters of base diesel, depending on whether performance rig tests are included. Exact quantities should be confirmed with the laboratory before submission.

How long does a complete evaluation take?

Basic physicochemical and no-harm testing generally takes five to ten working days. Programs including engine or rig-based detergent and cetane performance evaluation may require two to four weeks because of comparative base fuel testing.

Is an accredited report necessary?

For regulatory submission, market supervision and legal purposes in China, reports bearing CMA accreditation are required, while CNAS accreditation provides international recognition through ILAC mutual recognition arrangements. Voluntary R&D screening may use non-accredited methods, but accredited third-party laboratories are strongly recommended for any compliance claim.