9902.10.22 - Mixtures of hydrotreated neutral petroleum oils C20 - C50, of a kind used as viscosity improvers (CAS No. 72623-87-1) (provided for in subheading 3811.21.00).

This HTS category, 9902.10.22, specifically covers mixtures of hydrotreated neutral petroleum oils with a carbon chain length ranging from C20 to C50. These particular oils are classified here due to their intended use as viscosity improvers in various industrial applications. The inclusion of the CAS number (72623-87-1) provides a precise identifier for these chemical substances. It is important to note that while these oils are petroleum-derived, their specialized function as viscosity improvers and their presence within Chapter 99 indicate a specific temporary or special classification provision.

Unlike the preceding sibling categories, which broadly cover live animals from horses to poultry, this classification pertains exclusively to specific chemical products. The broad scope of Chapter 99, encompassing temporary legislation and special classification provisions, differentiates it from the core product chapters of the HTS that define goods based on their fundamental nature and origin. This section is designed to accommodate items that may fall outside standard tariff treatments due to trade agreements, temporary restrictions, or other legislative actions.

As this is a leaf node, there are no further subcategories under 9902.10.22. The classification is definitive for the described petroleum oil mixtures when used as viscosity improvers. The parenthetical note referencing subheading 3811.21.00 clarifies that these specific oils, when classified under this temporary provision, are otherwise provided for within the broader category of lubricating preparations. This highlights the interplay between temporary and permanent tariff classifications, where items may have dual classifications depending on specific import circumstances or policy directives.