If you’re an automobile owner looking to add oil to your engine, understanding the types of oil on the market is essential. The debate about whether or not you can mix a lighter oil with a heavier one is an important question. For instance, can you mix 5W-30 and 10W-30?
You can mix 5W-30 and 10W-30 engine oils, but it’s not necessarily ideal. These two oils will flow at different rates due to their weight difference; however, the difference isn’t significant enough to cause any damage to your engine. When mixing oils, it’s recommended to use additives to encourage blending.
In this article, I’ll go over the correct way to mix two different oils like 5W-30 and 10W-30 together. I’ll also discuss what qualifies two oils to be successfully mixed together and provide critical points to remember when mixing and using two different types of oil in your engine.

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How is 5W-30 Oil Different from 10W-30 Oil?
The numbers on the oil label refer to the weight of the oil (viscosity.) The first number is for winter, and it refers to how quickly the oil will flow at cold temperatures. The second number is for summer, and it refers to how quickly the oil will flow at high temperatures.
Mixing a heavier oil with a much lighter one can cause issues because they flow at different rates depending upon the temperature, and this could cause problems in your engine if not done correctly. You should be aware that the oil you are using is the correct weight for the season.
5W-30 oil is different from 10W-30 oil most notably in the weight of the oil in winter. The lower the number in front of the W, the lighter the oil in cold temperatures. This means that a 10 weight oil flows more slowly than a 5 weight oil.
Therefore, if you do mix oils together, it’s important to use oils with similar weights that’ll flow at the same rate. Here are a few important things to keep in mind:
- Never mix synthetic oils with conventional oils.
- Make sure that both types of oil are similar weights so they will flow at the same rate.
- Verify that both oils are of the correct weight for the season before adding them together to avoid causing damage to your engine.
Keeping these points in mind can help you avoid issues when mixing oil types. However, it’s essential to pay close attention if you decide to mix oils. If you’re unsure whether or not to mix two different types of oil, it’s best to consult an expert for advice on the proper process.
Side Effects of Using the Wrong Oil in Your Car
You can’t use any weight of oil in your car; rather, you must use the same oil weight as is listed in your owner’s manual. If you don’t have an owner’s manual, the recommended weight of oil should also be printed on the stickers under the hood or on the engine.
Without an owner’s manual, it could be challenging to determine which oil weight your engine requires. If you put too heavy or too light of weight in your car, your engine could be negatively affected. If needed, go online to source out this information.
There can be damaging effects if you have used the wrong oil type for your car. Specifically, it could cause damage to the motor and decrease the lifespan of your vehicle.
Some of the most common side effects of using the wrong weight of oil are:
- Reduced fuel economy
- Increased engine wear and tear
- Slower acceleration
- Poor performance in cold weather climates
- Difficulty starting your car in cold weather conditions
In short, if you use too heavy of a weight, your engine may not be able to start. If you use too light of an oil, your engine will wear down more quickly than it should. Additionally, if you mix two different types of oil with different weights, your motor may not run as smoothly as it should.
These are just a few examples, and there can be other side effects as well. If you are using the wrong type of oil in your car, it’s essential to stop and switch to the correct weight as soon as possible.
The Correct Way to Mix Two Different Types of Oil
To combine oils with different weights, first pour the lighter-weight oil into the engine. Then, pour the heavier weight oil on top of the lighter oil. This helps to ensure that both oils are mixed correctly.
Keep in mind that you should never mix synthetic oils with conventional oils.
As I’ve mentioned, if you’re going to mix two different types of oil, it’s important to use oils with similar weights so they flow at the same rate. It’s also crucial to verify that both oils are of the correct weight for the season before adding them together. This will help to prevent any damage done to your engine.
Benefits of Using Oil Additives When Mixing Oils
An oil additive can be used to mix two different types of oils. The first benefit is that it helps the heavier weight oil flow more quickly through the system, making it easier to integrate with lighter weight fluids.
Another benefit is an enhanced protection from wear and tear for your engine from wear Additives are typically made from synthetic materials made to help with this very purpose.
When using an oil additive, it’s important to use the proper additive that’s made for the type of oil you’re using. For example, if you use synthetic oil, you should use a synthetic additive. On the other hand, if you use a mineral-based oil, you should use a mineral-based additive. Using the wrong type of additive could damage your engine.
Additional Tips To Keep in Mind When Mixing Oils
There are a few other things you should keep in mind when you mix different types of oil:
- It’s important to use oils that are similar in weight when using two different oil weights. This means that the two oils should be either light or heavy, but not one of each. When mixing oils with significant differences in weight together, the engine may not run as smoothly as it should.
- Always follow the bottle’s directions carefully when adding an additive to your oil. Failure to add the additive correctly can cause damage to your engine.
- Be sure to check the oil level once you’re finished mixing the two oils. Check the level after running your car for a while. If there isn’t enough oil weight inside the tank, mix another type of oil until you reach the level recommended by your manufacturer.
If you have any other questions about mixing oils together, don’t hesitate to contact a mechanic or your car’s manufacturer. They’ll help you understand the best way to mix oil for your vehicle.
Mixing 5W-30 and 5W-20: The Verdict
You can mix 5W-30 and 10W-30 or combine a lighter-weight oil with a heavier one, in general. It’s not necessarily ideal, but doing so won’t cause harm to your engine. These two oils only have a difference of five points on the scale, so mixing can be done successfully. Furthermore, when using oil additives, make sure the additive is made for your oil type.
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