Any moving parts in a machine require lubrication in order to minimize the wear and tear of surfaces that are in contact with each other. In addition to lubricating, oils also clean, improve sealing, prevent corrosion, as well as cooling the machine by transferring the heat away. This clearly shows the importance of using oil as recommended for your particular machine or engine. For vehicles, a number of oils are available. The common ones are 5w30 and10w40.
5w30 motor oil is synthetic motor oil that has a viscosity of 5 in low temperatures and viscosity of 30 at higher temperatures, usually 100 degree Celsius.
10w40 motor oil is synthetic motor oil that has a viscosity of 10 in low temperatures and viscosity of 40 at higher temperatures, usually 100 degree Celsius.
|5w30 motor oil||10w40 motor oil|
|Less viscous||More viscous|
|Has a viscosity of 5 at low temperatures||Has a viscosity of 10 at low temperatures|
|Has a viscosity of 30 at high temperatures||Has a viscosity of 40 at high temperatures|
The difference is in the viscosity of each at different temperatures.
The numbers of the oils depicts their respective viscosities at low and high temperatures. The first number shows the oil’s viscosity at low temperatures and the last number shows the oil’s viscosity at high temperatures. The ‘w’ means winter, implying the viscosity at which the oil will flow when the car is starting or at low temperatures. The 5w30 oil will flow better at low temperatures than the 10w40 oil. This means that the 5w30 oil will protect the engine better at low temperatures, usually when the engine is just starting or during weather conditions such as winter. At high temperatures, the 5w30 oil is thinner than that of 10w40 since 30 is lower than 40. These numbers, however, do not depict the actual viscosities of the oils at extreme temperatures.
Please look at this video for more information about the differences of the various oils and also the best one for your car: