1. Anti-Wear Agents: These additives form a protective film over metal surfaces to reduce friction and prevent wear and tear, especially under high-pressure conditions.
2. Corrosion Inhibitors: They prevent rust and corrosion by protecting metal parts from moisture and contaminants
3. Viscosity Modifiers: Additives that help maintain the oil's viscosity across a wide range of temperatures, ensuring that it flows well at both low and high temperatures.
4. Detergents and Dispersants: These additives keep engine parts clean by preventing the formation of sludge and varnish. They help in dispersing contaminants and soot, allowing them to stay suspended in the oil.
5. Foam Control Agents: These prevent the formation of foam, which can reduce the effectiveness of lubrication and lead to overheating.
6. Oxidation Inhibitors: They slow down the oil's degradation by reducing the rate of oxidation, which can result from exposure to high temperatures.
   
7. Friction Modifiers: These help reduce friction between moving parts, improving the oil’s efficiency and performance.

The "brown" color is likely a characteristic of the specific type of additive package used, as some additives can give the oil a brownish tint. The color does not necessarily indicate a specific function, but it could be linked to certain chemical components or the oil base used.