The main difference between C2 and C3 engine oils lies in their specific quality grades. Both C2 and C3 engine oils are certified according to the European ACEA engine oil quality standard, falling under the third major category of European engine oils, known as Category C. Category C oils are further subdivided into five specific quality levels, from C1 to C5, with C5 being the highest. C2 and C3 represent the second and third levels within the Category C oils. These specifications do not imply that one oil is inherently better or worse than another; they simply indicate different standards suitable for different vehicles. For example, the difference between C2 and C3 lies in the minimum high-temperature high-shear viscosity requirements. Car owners can refer to these parameters and consider factors such as driving conditions, personal driving habits, and the vehicle's maintenance manual to select the most suitable oil. Choosing the right oil ensures optimal engine protection, extends engine lifespan, and maximizes engine performance. The functions and roles of engine oil are as follows: Friction and High-Temperature Reduction: A sufficiently thick oil film separates the surfaces of moving parts, reducing wear and tear. Sealing Effect: The oil forms a seal between the piston rings and pistons, minimizing gas leakage and preventing contaminants from entering. Rust Prevention: The lubricant adheres to part surfaces, shielding them from water, air, acidic substances, and harmful gases. Cushioning Effect: When cylinder pressure rises sharply, the sudden increase in load on pistons, piston rings, connecting rods, and crankshaft bearings is mitigated through lubrication, cushioning the impact. Cleaning Effect: High-quality oil carries away carbon deposits, sludge, and metal wear particles from engine components, circulating them back to the oil pan and flushing out contaminants from part surfaces.
