HS Code 38.11 – Anti-knock preparations, oxidation and gum inhibitors, viscosity improvers, anti-corrosive preparations and the like, for mineral oils (including gasoline) or other liquids used for the same purposes

HS code 3811 is a 4-digit heading in the Harmonized System that covers: Anti-knock preparations, oxidation and gum inhibitors, viscosity improvers, anti-corrosive preparations and the like, for mineral oils (including gasoline) or other liquids used for the same purposes. Heading 3811 covers a critical category of chemical preparations designed to enhance the performance and longevity of mineral oils, including gasoline, and other liquids used for similar purposes. This encompasses anti-knock preparations that improve fuel efficiency and prevent engine damage, oxidation and gum inhibitors that prevent fuel degradation and deposit formation, viscosity improvers that maintain lubricant performance across temperature ranges, and anti-corrosive preparations that protect engine components from rust and wear. The 'and the like' clause extends the scope to similar additives serving analogous functions. These are *preparations*, meaning they are formulated mixtures, not single chemical compounds, and are specifically intended *for mineral oils or other liquids used for the same purposes*. This distinction is vital for customs classification, preventing confusion with raw chemicals (Chapters 28/29) or the mineral oils themselves (Chapter 27). For importers, exporters, and trade compliance professionals, correct classification under 3811 ensures adherence to specific regulations governing fuel and lubricant additives, proper duty assessment, and compliance with environmental standards. These preparations are indispensable to the global energy sector, automotive industry, and industrial machinery, significantly impacting performance, efficiency, and environmental emissions. This heading's inclusion in Chapter 38 underscores its nature as a specialized chemical product.

Octane boosters, cetane improvers, fuel stabilizers, engine oil additives, transmission fluid additives, pour point depressants, viscosity index improvers, corrosion inhibitors for fuels, anti-wear additives for lubricants, diesel fuel treatments, gasoline additives, lubricant antioxidants, friction modifiers for oils, dispersants for engine oils, detergents for fuels, anti-foaming agents for lubricants, cold flow improvers for diesel, extreme pressure additives, rust preventatives for fuels, fuel system cleaners (additive type), lubricity improvers, ashless dispersants, synthetic lubricant base stock enhancers.

A common classification mistake for HS 3811 is confusing these specialized preparations with the mineral oils or fuels they are intended to treat, which fall under Chapter 27 (Mineral fuels, mineral oils and products of their distillation). Another error is classifying the individual chemical components of these preparations under Chapter 29 (Organic chemicals) or 28 (Inorganic chemicals), rather than as formulated mixtures. The key is that 3811 covers *preparations* specifically designed to *modify the properties of mineral oils or similar liquids*, not the raw chemicals themselves or the final fuel/lubricant products. Traders must verify the product's compound nature and its explicit function as an additive to ensure accurate classification.

In 2025, the top exporters of HS code 3811 in UN Comtrade data were the United States ($3.0B, 22% of world exports), France ($2.5B) and Singapore ($2.1B). World exports came to about $13.3B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.

In 2025, the top importers of HS code 3811 in UN Comtrade data were China ($1.0B, 7.2% of world imports), Germany ($1.0B) and Singapore ($943M). World imports came to about $14.6B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.

HS code 3811 is a 4-digit heading under Chapter 38 of the Harmonized System. The first 2 digits (38) identify the chapter, and digits 3-4 (11) specify the heading. This code contains multiple 6-digit subheadings for precise product classification.