Should a turbocharged engine use 5w30 or 40 oil?
2 Answers
Turbocharged engines require at least 5w30 oil, but 40 viscosity oil can also be used. Turbocharged engines operate at higher temperatures and pressures, necessitating oil with higher viscosity to provide adequate lubrication. During normal engine operation, the oil forms a protective film on the surfaces of engine components, reducing wear between parts. If the oil viscosity is too low, it cannot form a stable protective film on engine components, which would accelerate engine wear and reduce its service life.
Having driven turbocharged cars for many years, I find 5w40 oil more reliable. Turbos operate under high temperatures and pressures, requiring oil that can withstand heat and provide protection. 5w40 has higher high-temperature viscosity, forming a stable oil film during high-speed rotation. In comparison, 5w30 offers quicker cold starts but tends to thin out during aggressive driving, potentially causing insufficient lubrication for turbo bearings and accelerating wear. Especially for older vehicles or those frequently used for long-distance driving, 40-grade is more dependable. However, the manufacturer's manual is the ultimate authority—each car's design differs, and some originally specify 30-grade oil, so avoid switching to higher viscosity. I regularly check the dipstick; if I notice viscosity deteriorating quickly, I switch to a better brand—it's hassle-free and safer. After all, turbo repairs are prohibitively expensive.
