Buyers must prioritize Viscosity Grade (SAE), such as 5W-30 or 10W-40, to ensure compatibility with specific engine climates. It is critical to verify Performance Categories like API (American Petroleum Institute) service symbols (e.g., SP, SN) or ACEA (European Automobile Manufacturers' Association) sequences (e.g., A3/B4, C3). Additionally, distinguish between Full Synthetic, Semi-Synthetic, and Mineral oils, as synthetic options offer superior thermal stability and oxidation resistance for high-performance or heavy-duty applications.