Engine oils are divided into categories or grades based on their thickness level. The higher the grade of the oil, the thicker it is. Hence, the main difference between 10W-30 grade and 20W-40 grade is that the latter is thicker than the former.

Now, thicker oil offers a higher amount of lubrication and wear protection, since it creates a thicker barrier between the moving parts of the engine. On the other hand, thicker oil also performs less efficiently in colder temperatures since the cold makes the oil even more viscous.

Keeping this in mind, the overall effect of replacing 10W-30 with 20W-40 or any other thicker oil, will be better lubrication and protection of the engine. However, when changing the engine oil of any vehicle, it is recommended that you stick to the manufacturer’s recommended grade or that mentioned in the owner’s manual.

What oil can I use instead of 10W-30?

It is generally recommended in the automobile industry to only use the engine oil grade that the manufacturer has recommended for the particular model of vehicle you own.

However, there can be times when that grade of oil is not available and in times like these, you can change the grade of oil you use in the engine. When replacing your current oil with some other grade, it is best to find a grade that is closest to the original.

In the case of 10W-30, grades like 5W-30 or 20W-40, are quite close to the viscosity of the original oil. Hence, these grades can generally be used instead of 10W-30 without any damage to the engine. 

What oil is thicker than 10W-20?

Oil grades are determined on the basis of the viscosity of the oil. This means that the numbers in the grade indicate the thickness level of the engine oil. However, viscosity is not stable. 

Oil tends to become thinner in the heat and become thicker in the cold. Since thickness is also dependent on the temperature, oil grades have two levels.

For instance, in the case of 10W-20, the first level i.e. 10 indicates the thickness level of the oil at lower temperatures, while the second level i.e. 20 indicates the viscosity in normal operating temperatures.

The higher the grade level, the thicker the oil. Thus, any oil that is a higher grade is thicker than 10W-20. This includes oil grades like 10W-40, 10W-50, 20W-30, 20W-40, and so on. 

Is thicker oil better for older engines?

Thicker oils provide more protection and lubrication as compared to thinner oils.

This is because a more viscous oil creates a thick barrier between the moving parts of the engine. This barrier reduces friction and protects internal parts from wear and tear.

In new engines, thinner oils work well since the parts are new and do not need extra protection.

However, in the case of older engines, thicker oils are preferred. This is because thicker oils can prevent excessive wear and tear that is frequent in old engines. Furthermore, thicker oils have less chances of leakage and hence are preferred for older engines. 

Is synthetic oil bad for oil engines?

Engine oil comes in mainly three types – conventional motor oil, semi-synthetic oil and synthetic oil. Out of all these, synthetic oil is the latest technology that is fully manufactured in laboratories.

It is engineered to be perfect for protection and lubrication of the engine and is therefore far more effective than the other two types of oils. It lasts longer and is less prone to breaking down.

While most older cars used to use conventional engine oil, since synthetic oil is a recent advancement, it is not necessary that you use only conventional oil in your old car. Synthetic oil is suitable for all engine types and can be used without problems even in older engines. 

Will thicker oil damage my engine?

Both thick and thin oils have their own pros and cons.

Thicker oils offer more protection and lubrication but can also be responsible for lower fuel economy. On the other hand, thinner oils are great for fuel economy and low engine load, but they can cause higher levels of wear because they offer lower lubrication.

Each engine and vehicle comes with its own set of requirements from the engine oil. Vehicle owners are advised to adhere to the engine oil recommended by the manufacturer, listed in the owner’s manual.

The recommended grade is the best for your engine. That being said, in some cases, thicker oil can reduce mileage, give a higher load to the engine and hence even shorten the engine life. It is therefore best to use on the recommended oil grade, or one grade above or below that one.



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