These two types of oil are often seen when we search for a motor oil for our car. The difference is mainly the state of the cold oil, ie the viscosity.
The 5w40 is especially recommended for engines that are sporty and for short trips or to drive mainly in town. 5w40 means winter viscosity index 5 and hot viscosity index 40. The 5w40 is a synthetic oil compared to the 10w40 which is semi-synthesis.
The 10w40 is more for cars with average power and small city cars.
It is necessary to check about the compatibility with the engine in the guide book of the car.
Best 5w40 oil:
Castrol EDGE Turbo Diesel engine oil 5W-40 5L is a lubricant with great fluidity and great protection, suitable for high-performance, new generation or high-end engines. It is perfect for substantial power. Engine performance is optimized, as is its responsiveness.
Best 10w40 oil:
Shell Helix HX7 Lubricating Oil 10W-40 A3 / B4 is a quality oil that lasts over time. It has an effective cleaning action. It is compatible with catalysts. It is also suitable for injection diesel engines with turbo and intercooler without particulate filter.