Antiknock preparations — HTS 3811
Antiknock preparations, oxidation inhibitors, gum inhibitors, viscosity improvers, anti-corrosive preparations and other prepared additives, for mineral oils (including gasoline) or for other liquids used for the same purposes as mineral oils
Chapter 38 › Heading 3811
2026 HTS Rev 19 Synced Rules verified Operational
Written to help non-specialists understand this page. Rates, dates, and legal facts come from the official records above and on the linked source.
HTS heading 3811 is a broad product category for prepared chemical additives used with mineral oils, such as gasoline, diesel, lubricants, and similar liquids. It groups products that improve or protect fuel and oil, including antiknock preparations, oxidation or gum inhibitors, viscosity improvers, anti-corrosive preparations, and other additives with comparable intended uses.
To reach the correct 8-digit HTS code, start with the product’s primary function and intended liquid or fuel. The lower-level provisions commonly distinguish products by additive type, chemical composition, or other product characteristics. Read the full wording of the candidate subheadings, not just the heading title, and confirm that the product is a prepared additive for the covered use rather than a standalone chemical or a product classified elsewhere.
What to check
- Obtain the complete ingredient formula, technical data sheet, safety data sheet, and product specifications.
- Identify the additive’s principal function and the fuel, oil, or similar liquid for which it is designed.
- Check whether the tariff provisions distinguish the product by chemical material, additive type, or intended application.
- Compare the product’s actual composition and marketing description with the full text of each possible 8-digit provision.
- Ask a customs broker or request an official classification ruling when the formulation has multiple functions or the correct provision is uncertain.
HTS heading 3811 summary
Antiknock preparations is a 4-digit product category containing 4 published product-code lines in this snapshot. A heading does not carry one universal duty rate; classification must be narrowed to the line matching the product facts.
How to find your code in this category
A heading is a product category. To get the exact duty, narrow from this 4-digit heading to a sub-category (usually by material), then open the 8-digit code that matches your product.
Open any code in the tables below to see its exact duty rate, a duty calculator (enter your shipment value → estimated duty and landed cost), the rate-change history chart, and the country-by-country breakdown (including Section 301/232 add-on duties).
Why you have to click in: a single category can contain products with very different duties. The rate depends on the specific product — its material and construction — and on the country of origin, and those only get pinned down at the 8-digit code level. That is why this page points you to codes instead of showing one rate for the whole category.
Sub-categories
| Code | Description |
|---|---|
| 3811.11 | Based on lead compounds |
Product codes & duty rates
👇 Each row is a specific product code — click a blue code to open its full page with exact duty rates by country, the rate-history chart, and a duty calculator. 👉
| Code | Description | General (MFN) | Special | Column 2 |
|---|---|---|---|---|
| 3811.19.00.00 👉 | Other | 6.5% | Free | 3.7¢/kg + 60% |
| 3811.21.00.00 👉 | Containing petroleum oils or oils obtained from bituminous minerals | 6.5% | Free | 60% |
| 3811.29.00.00 👉 | Other | 6.5% | Free | 25% |
| 3811.90.00.00 👉 | Other | 6.5% | Free | 3.7¢/kg + 60% |
"Special" shows the free-trade-agreement rate; open a code to see exactly which countries qualify.
Common questions
What products fall under HTS heading 3811?
Antiknock preparations, oxidation inhibitors, gum inhibitors, viscosity improvers, anti-corrosive preparations and other prepared additives, for mineral oils (including gasoline) or for other liquids used for the same purposes as mineral oils. To classify a specific item you must pick the matching sub-category and 8-digit code above; the right choice usually depends on the material and construction of the product.
How do I choose the right code within this category?
Start from the sub-categories (typically divided by material—for example cotton versus man-made fibers), then open the active 8- or 10-digit code that matches the product. When unsure, a licensed customs broker or a CBP binding ruling can confirm the classification.
Reference information only, not customs, legal, or classification advice. Confirm the current code and rate against the official HTS before you import.