Product classification

HS code for Viscosity improvers: 3811.90

Oxidation and gum inhibitors, viscosity improvers, anti-corrosive preparations, other prepared additives for mineral oils or liquids used as mineral oils (including gasoline), n.e.c. in heading no. 3811.

Classification of viscosity improvers under HS 3811.90

Viscosity improvers are classified under HS code 3811.90. Heading 3811 covers prepared additives for mineral oils or for other liquids used for the same purposes as mineral oils. This includes anti-knock preparations, oxidation inhibitors, gum inhibitors, and viscosity improvers. While specific subheadings exist for anti-knock preparations based on lead compounds, viscosity improvers fall into the "other" category under 3811.90. These products are typically chemical mixtures or polymer solutions (such as polymethacrylates or olefin copolymers) designed to modify the flow characteristics of lubricants or fuels across different temperatures. Classification is driven by the intended use of the preparation as an additive for mineral oils, rather than the chemical identity of the individual components. However, the preparation must be "prepared," meaning it is a mixture or a specific chemical intended for use as an additive.

Covers
  • Viscosity index improvers (VII)
  • Lubricating oil additives for viscosity control
  • Prepared thickeners for mineral oils
  • Polymer-based viscosity modifiers in solvent
  • Multi-grade oil additive packages
Also under 3811.90
  • Lubrizol Anglamol
  • Afton HiTEC
  • Infineum P-series
  • BASF Keropur
  • Chevron Oronite OLOA

Codes often confused with 3811.90

Common mistake. Viscosity improvers are often misclassified in Chapters 39 (Plastics) if they are pure polymers. However, if they are prepared as additives for oil, Heading 3811 takes precedence. They may also be confused with HS code 2710 if they are already blended into a finished lubricating oil. Another confusion arises with HS code 3403 if the product is a lubricant itself rather than an additive.

38.11Anti-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 purposes27.10Petroleum oils and oils from bituminous minerals, not crude; preparations n.e.c, containing by weight 70% or more of petroleum oils or oils from bituminous minerals; these being the basic constituents of the preparations; waste oils34.03Lubricating preparations and those used in oil or grease treatment of textile and similar materials; excluding preparations containing 70% or more (by weight) of petroleum or bituminous mineral oils

Top exporters and importers of HS 381190 (the code used for viscosity improvers), 2025

In 2025, the largest exporter of HS 381190 (the code used for viscosity improvers) in UN Comtrade data was the United States, with 28% of world exports; the largest importer in UN Comtrade data was Canada, with 6.8% of world imports. Countries that did not report 2025 data are estimated from partner records, which can understate them.

Figures cover everything classified under HS 381190, not only viscosity improvers.

Top exporters 2025 · share of world exports

  1. 1 United States $720M
  2. 2 Germany $582M
  3. 3 India $188M

World total: $2.5B Reported figures on UN Comtrade ↗

Top importers 2025 · share of world imports

  1. 1 Canada $186M
  2. 2 United States $169M
  3. 3 Singapore $146M

World total: $2.7B Reported figures on UN Comtrade ↗

How these figures are built

109 countries reported 2025 trade to UN Comtrade in HS 2022, and their own totals are used. Countries that did not report are estimated from what other countries recorded trading with them. Those estimates miss trade with other non-reporting countries, so they can be low, and a non-reporting country can rank higher than shown or be missing from the list. World totals add both and leave out trade between two non-reporting countries. Figures are in current US dollars; reported imports are mostly valued CIF and exports FOB, and exports include re-exports. The UN Comtrade links show the underlying records; they can also list a few reporters left out here (regional groups and older HS editions).

Source: UN Comtrade (United Nations Statistics Division), 2025 annual data.

Brazil NCM codes for viscosity improvers

Brazil splits HS 3811.90 into 2 NCM codes. Pick the one that matches your product:

Source: Siscomex NCM table, updated Oct 2026. The Portuguese text on each NCM page is the official one.

Questions about viscosity improvers

What is the HS code for Viscosity improvers?

The HS code for Viscosity improvers is 381190 (Oxidation and gum inhibitors, viscosity improvers, anti-corrosive preparations, other prepared additives for mineral oils or liquids used as mineral oils (including gasoline), n.e.c. in heading no. 3811). Viscosity improvers for mineral oils are classified under HS code 3811.90.

How do I classify Viscosity improvers for customs?

Viscosity improvers is classified under HS code 381190 — Oxidation and gum inhibitors, viscosity improvers, anti-corrosive preparations, other prepared additives for mineral oils or liquids used as mineral oils (including gasoline), n.e.c. in heading no. 3811. This is a 6-digit subheading level code.

Are viscosity improvers classified as polymers in Chapter 39?

No, when they are prepared specifically as additives for mineral oils, they are classified under 3811 per the Explanatory Notes to Heading 3811.

Which countries are the top exporters of viscosity improvers (HS 381190)?

In 2025, the top exporters of HS 381190 (the code used for viscosity improvers) in UN Comtrade data were the United States ($720M, 28% of world exports), Germany ($582M) and India ($188M). World exports came to about $2.5B, 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.

Which countries are the top importers of viscosity improvers (HS 381190)?

In 2025, the top importers of HS 381190 (the code used for viscosity improvers) in UN Comtrade data were Canada ($186M, 6.8% of world imports), the United States ($169M) and Singapore ($146M). World imports came to about $2.7B, 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.

Is the HS code for Viscosity improvers the same in all countries?

The base HS code 381190 for Viscosity improvers is internationally standardized for the first 6 digits across 200+ countries. Individual countries may add additional digits for national tariff lines and specific classifications.

What is the NCM code for viscosity improvers in Brazil?

Brazil splits HS 381190 into 2 NCM codes, so the right one for viscosity improvers depends on the product's details: 3811.90.10 (Ashless dispersants for fuel oils), 3811.90.90 (Other mineral oil additives and inhibitors).