Can a Four-Stroke Motorcycle Use Car Engine Oil?
2 Answers
No. In car engines, the lubrication of the engine, transmission, and clutch is separate, with the oil temperature in the crankcase ranging between 75-90°C. Here are the reasons why car engine oil should not be used: 1. Different Structures. In car engines, the lubrication of the engine, transmission, and clutch is separate, with the oil temperature in the crankcase ranging between 75-90°C. However, in motorcycle engines, components such as the wet multi-plate clutch, high-speed and transmission gears, shift mechanism, piston, cylinder, intake and exhaust valves, and other moving parts are all housed within the same structure and share the same oil volume. Additionally, the friction plates of the clutch and the rotation of the transmission gears generate significant heat, causing the oil temperature in the crankcase to reach as high as 80-120°C. 2. Differences in Cooling Effects. Car engines typically hold about 5-7L of oil, while motorcycle engines only hold around 1L. Oil needs sufficient flow to effectively dissipate heat. The amount of oil significantly impacts cooling performance. Moreover, most motorcycles rely on air cooling, which is far less efficient than the radiator-based liquid cooling systems in cars. Even liquid-cooled motorcycles have smaller coolant capacities than cars, resulting in poorer heat dissipation. This inevitably leads to much higher oil temperatures in motorcycle engines compared to car engines. 3. Power per Liter. The power output per liter for cars is generally 60-80Kw/L, while for motorcycles, it is 100-120Kw/L—about 1.5 times higher than cars. In terms of power-to-volume ratio, motorcycles are twice as powerful as cars. Car engines typically operate at 3000-5000r/min, whereas motorcycle engines run at 8000-11000r/min, which is 50% to 120% higher. At maximum power output, motorcycle engines reach 10000-15000r/min, while car engines peak at 4000-5000r/min, rarely exceeding 6000r/min. 4. Engine Stress. Due to differing driving conditions and technical requirements, motorcycle engines endure 3-4 times higher stress levels than car engines. Motorcycles are lightweight and often operate at speeds corresponding to maximum power or torque output, leading to higher engine temperatures and greater wear. This demonstrates that motorcycles operate in much harsher conditions than cars.
Actually, many motorcycle enthusiasts have discussed this issue. From my experience, it's best not to use regular car engine oil for four-stroke motorcycles. Although both are graded according to API standards, motorcycle engines run at higher RPMs and also need to lubricate the clutch. Car engine oil isn't designed for wet clutches, which can easily lead to slippage and affect riding safety. I've also heard from mechanics that long-term use of car engine oil can cause premature wear on motorcycle chains due to differences in anti-wear additives. Additionally, environmental factors matter: car engine oil has poor viscosity control in low temperatures, which may cause starting difficulties for motorcycles. Some people try to save money by mixing oils, but end up losing more than they gain. I personally tried using car oil once or twice in emergencies and noticed the engine sound became louder, so I immediately switched back to motorcycle-specific oil. Now for maintenance, I only choose oils with JASO MA certification – they're more expensive but ensure safety. In short, don't cut corners and overlook details. Motorcycles and cars have significant design differences, and engine oil needs to be tailored accordingly.
