Unveiling the Secrets of Engine Oil Blending: Can You Mix 5W-20 and 5W-30?

Mixing engine oils with different viscosity grades is a matter of confusion among vehicle owners. You may find it tempting to mix 5W-20 oil with 5W-30, but the experts and manufacturers do not recommend it. Engine oils are prepared by following specific guidelines and formulated to meet specific needs; mixing them can amend their properties. Now, you know mixing 5W-20 and 5W-30 oils is not recommended. You might be wondering, “Why?” Here, we’ll explore the effects of mixing 5W-20 and 5W-30 on your vehicle engine with some safety precautions. 

Whats the Difference?

Castrol Edge 5W-30

It is important to understand the purpose of specific engine oil to manage its usage. The name of engine oil is designed to denote viscosity. The letter “W” represents winter, and the number “5” before it represents the way engine oil behaves in winter. With a temperature change, the engine oil can change its properties, especially viscosity. 

Moreover, we have “20” and “30” numbers in the name of 5W-20 and 5W-30 oils, respectively, which suggests how oil reacts to high temperatures. At higher temperatures, 5W-20 might be functional to some extent but not as much as 5W-30. It has a thicker viscosity, so it properly lubricates the parts of the engine at higher temperatures and protects them from wear and tear. 

Castrol Edge 5W-20

On the other hand, 5W-20 is best for lower temperatures because of its thinner viscosity. The 5W-20 is thin, so it can easily lubricate the fine parts of the engine, with the oil reaching the deepest parts. It functions perfectly at a lower temperature, while at a higher temperature, it is too thin to lubricate parts of the engine properly. 

Assessing the Safety of Mixing 5W-20 with 5W-30

Usually, it is safe to mix 5W-20 and 5W-30 until you follow the recommendations provided by your vehicle manufacturer. Specific engines support specific types of engine oil, and it is mentioned in the manufacturer’s manual. It is ideal to use the exact oil rated for your vehicle engine or the one with the closest similarity. 

In some emergencies, you can mix 5W-20 and 5W-30 oils, and it will not cause any harm to your engine. Occasional or emergency mixing of engine oils of the same brand and API service level will not damage the engine, but long-term use can reduce the performance of your engine. You might notice some difficulty in starting the engine. Plus, it behaves differently in warm and cold temperatures.

Precautions of Mixing

Following are some precautionary measures you should know before mixing them to avoid any damage to your engine:

  • Do not mix 5W-20 and 5W-30 in equal quantities because it nullifies most of the benefits and can harm your engine. It will become harder for the engine to start and work. As a result, the engine heats up more than usual.
  • You should only mix them to top off the oil in your engine. If you have 5W-20 engine oil, you can use 5W-30 oil to reach the correct mark on the dipstick and vice versa. 
  • Do not mix 5W-20 oil with 5W-30 oil if you live in a hot climate. Only 5W-30 should be used at high temperatures, while 5W-20 should be used at lower temperatures.

As recommended by the experts, thicker oil should be more in ratio than thinner oil. If you need to top off oil in a 5W-30 engine that supports 5W-30 oil, you can use 5W-20 oil. As 5W-30 is the heavier oil, use two portions of this oil, and 5W-20 is the lighter one, so use one portion of it. This is a good way to mix 5W-30 and 5W-20 engine oils in emergencies.

Effects of Mixing These Two Oils

5W-20 and 5W-30 both have different viscosity and additive components, so even if they are mixed, they float separately and don’t form a single mixture. Your engine will not be immediately affected by this mixture of oils, but it can affect you in the long run. With time, it can lead to sludge formation, overheating, oil leaks, and deposits in the engine. 

The overheating of the engine can damage gaskets and seals, which leads to leaks. The leaks can put you in serious trouble when smaller leaks become larger ones later on. Moreover, older and more worn engines will face some difficulty in starting. This is a rare effect of mixing 5W-20 and 5W-30 oil, yet it is important to mention. 

Amazon.com: Castrol Edge 5W-20 Advanced Full Synthetic Motor Oil, 5 Quarts,  Pack of 3 : Automotive

For better performance, make sure to mix both oils from the same brand. However, due to incompatible additives in both 5W20 and 5W30 oil, there is no guarantee of better engine performance. This mixture of oils might not properly lubricate the parts of the engine, which results in unpleasant noises. Due to the grinding of parts, they will wear prematurely. 

Can You Use 5W-20 Instead of 5W-30?

The engine compatible with 5W-30 will work best with the same oil. If you add 5W-20 instead of 5W-30, your engine will heat up early and lead to wear and tear of engine parts. However, if your engine is old, you can use 5W-20 instead of 5W-30. As it is less viscous, so easier to process in worn engines. There is another situation where you can use 5W-20 when the oil pan is coagulated. The lighter weight of 5W-20 will not add to the clumping and reach overheated parts much faster. 

Can You Use 5W-30 Instead of 5W-20?

5W-30 has a higher viscosity and is too thick to properly lubricate the parts of the 5W-20 engine, which requires a thinner oil. Improper lubrication will increase the resistance between the parts of the engine, which leads to poor performance and premature wearing. However, in an emergency, you can use 5W-30 oil in a mixture with 5W-20 oil, as mentioned above. 5W-30 is thicker, so it burns more, and you will experience a decrease in fuel economy as well as in horsepower. Moreover, using 5W-30 instead of 5W-20 will lead to fatal engine damage in the long run. 

What Are Expert Insights on Mixing these Oils?

There seems to be some disagreement among experts. Some state that mixing both oils will not harm your engine, while others state great damage to the engine by mixing 5W-20 and 5W-30. Regardless of this disagreement, all experts recommend sticking to the engine oil mentioned in the manufacturer’s manual. 

Experts also state that both oils have their benefits, and mixing them will be of no advantage. Use them separately according to your engine to get maximum engine performance. 5W-30 engine oil has thick viscosity, and it is best when you want high mileage or drive in warmer environments. On the other hand, the 5W-20 has a thinner viscosity and is best for lubricating the engine, which protects it in high mileage situations while driving in colder environments.

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