4T refers to the specialized oil designed for 4-stroke engines, while 2-stroke motorcycles should use dedicated 2-stroke oil. The "T" stands for the first letter of the English word "stroke". Choosing the right 4T motorcycle oil is crucial, with the primary selection criteria being viscosity grade and lubrication level. The details are as follows: Viscosity Grade: 4T oils are categorized into single-grade and multi-grade oils. Single-grade oils are suitable for narrow temperature ranges, such as SAE10W for winter (-10°C to 15°C) and SEA for summer (15°C to 40°C). Multi-grade oils (also called composite oils) combine both characteristics and can be used year-round, like SAE10W/40 (25°C to 40°C). From a lubrication perspective, multi-grade oils contain various additives (such as anti-oxidation/corrosion agents and detergent dispersants), making them superior to single-grade oils. The selection of multi-grade oils depends on ambient temperature: SAE5W/30 is antifreeze oil for northern winters, while SAE20W/50 is suitable for southern summers. Commonly used specifications include SAE10 and SAE15W/40; for heavier vehicle loads, SAE20W/40 can be chosen. Lubrication Level: According to the API (American Petroleum Institute) standard, the minimum acceptable grade for motorcycle 4T oil is SD, with higher grades being SF (high-grade) and SG (wear-resistant). Grades above SG are synthetic oils, typically used for multi-cylinder, multi-valve racing motorcycles. For general users, SF grade is recommended, while SG grade is preferable if conditions allow. Higher-grade oils extend oil change intervals: typically 1,000 km for SE, 1,500 km for SF, and 2,000 km for SG.
