5w30 vs 10w30 – Which Is Better?

Motor oil is the lifeline of an engine and something that a lot of people take for granted. The assumption that oil is just used for lubricating, and not for enhancing the performance of a vehicle may prove to be wrong in the long run. If you really understand the basics of what oil does, what it is designed to do, and why it is important for the maintenance of your car, then you can go a long way in maximizing the health and lifespan of your vehicle.

The viscosity or thickness of motor oil determines its ability to flow well through the engine. The higher the first number, the thicker or more viscous the oil will be. The Society of Automotive Engineers (SAE) has assigned different statistical codes to different motor oils for the purpose of determining their viscosity. Thin liquids with a water-like consistency are assigned a lower viscosity value, while thick liquids with a honey-like consistency are assigned a higher value.

Therefore, if you live in a region where the temperature is usually very low or freezing, you should go for thin grade oil, such as 5w30. This is because they take much less time to heat up and are thus ready to flow through. On the other hand, thicker motor oils, such as 10w30, require more time before they are finally warmed up and are thus best suited for warmer environments. If you are not sure which viscosity is best suited to your vehicle, you can always refer to the top of the crankcase, which will have all the relevant information.

The first numerical, in this case, 5 and 10, are indicating how easy it is for the oil to flow through the engine at low temperatures. The lesser the number, the thinner the motor oil: 5 travels more smoothly and quicker than 10, a 10 better than 20, etc. A lower number indicates a lower viscosity, which means that the motor oil will offer faster protection to the engine’s internal components.

The second numerical, in this case, 30, is indicative of the oil’s thickness when it reaches high/operating temperatures. Thicker and high-viscosity oil will better adhere to mechanical parts when subjected to high stress and pressure and can resist higher temperatures before becoming thinner beyond its operational viscosity, which in simpler words means its ability to provide ample protection to the internal components.

When it comes to the difference between the two oils, it’ is their cold flowability. What this means is that a 10w30 will move much slower as compared to 5w30 motor during cold start-ups. However, at high temperatures, both motor oils will have the same level of viscosity, which is 30, and will travel through the engine and protect its parts in a similar manner.

If the motor oil will remain in the engine throughout the winter period and you live in a colder region, the recommended oil for you is 5w30. However, if it will remain in the engine during the warm summer months, then go for 10w30. Here are some of the important things to keep in mind:

On the other hand, 10w30 motor oil:

If you live in a colder environment, you will find that 10w30 motor oil flows much slower as compared to 5w30. This can both be of advantage and disadvantage. A more viscous oil, such as 10w30, will seal better than low viscosity oil, such as the 5w30. Thicker motor oil also offers better lubrication of key engine parts. However, thicker oils also put more drag on these engine parts, thus slowing down the engine performance. This excess resistance by motor oil can increase the consumption of fuel and also thus minimize fuel efficiency.