Category Code Category Name
Fuel
Solvents and Chemical Raw Materials
Lubricants and related products
W Wax
Bitumen
Carbon Graphite
In the same year as the promulgation of the standard GB 498-87, China issued GB 7631.1-87 "Classification of Lubricants and Related Products (L) - Part: General Grouping." GB 7631.1-87 was formulated based on the provisions of GB 498-87 "General Classification of Petroleum Products and Lubricants" and replaced GB 500-65, being equivalent to ISO 6743/0-1981 "Classification of Lubricants, Industrial Lubricants, and Related Products (L Class) - Part 0: General Grouping." This standard, following the principle of including as many applications of lubricants and related products as possible, divides lubricants into 19 groups. The names and codes of the groups are listed in Table 4.
On the surface, moisture is not easily permeable through a fully sealed drum lid into the oil drum. However, for drums stored outdoors, they are exposed to intense sunlight during the day and cooler temperatures at night. This thermal expansion and contraction affects the air pressure inside the drum; it's slightly above atmospheric pressure during the day and nearly a vacuum at night. This daily pressure fluctuation creates a "breathing" effect, where some air is "exhaled" out of the drum during the day and air is "inhaled" back into the drum at night. If the drum lid is submerged in water, it's inevitable that moisture will enter the drum with the air at night. Accumulated over time, the amount of water mixed with the oil can be quite substantial.

Mineral base oils are refined from crude oil. The main production processes of lubricant base oils include atmospheric and vacuum distillation, solvent deasphalting, solvent refining, solvent dewaxing, and clay or hydrorefining. In 1995, the current lubricant base oil standards in our country were revised, mainly modifying the classification method and adding two types of base oil standards: low-temperature pour point and deep refining. For the production of mineral-based lubricants, it is crucial to select the best crude oil.

Bulk oil storage in tanks inevitably leads to condensation and impurities being mixed in, eventually accumulating at the bottom and forming a sediment-like substance, contaminating the lubricating oil. Therefore, the tank bottom design should be V-shaped or inclined, and an exhaust plug should be installed to allow for the timely removal of residue. Within the possible scope, the interior of the oil tank should be cleaned regularly.

Temperature affects grease more than oil. Long-term exposure to high temperatures (e.g., direct sunlight) can cause the oil components in grease to separate. Therefore, grease drums should be stored indoors in preference, ideally placed upright with the opening upwards. The larger opening of the grease drums makes them more susceptible to dirt and water penetration. The lid should be tightly sealed immediately after use.
The standard categorizes base oils into five grades based on viscosity index: Low Viscosity Index (LVI), Medium Viscosity Index (MVI), High Viscosity Index (HVI), Very High Viscosity Index (VHVI), and Ultra High Viscosity Index (UHVI) base oils. According to their application scope, base oils are divided into general-purpose base oils and base oils. Base oils are further classified into low-foaming base oils (designated with "W") suitable for multi-grade engine oils, low-temperature hydraulic oils, and hydraulic transmission fluids, and highly refined base oils (designated with "S") suitable for turbine oils, industrial gear oils, and other products. Among them, HVI oils and MVI oils with VI>80 belong to Category I base oils in the international classification; MVI base oils and LVI base oils with VI<80 are not classified at all; VHVI and UHVI are classified as Category II and III base oils internationally, but there are no specific regulations regarding sulfur content and saturated hydrocarbons.