You might be in a situation where you’ve considered mixing oils from two distinct brands. It can happen if you have less oil in the tank and opt to fill it with a different brand of oil, or you just think that mixing oils give the most optimum performance. So, is mixing oil beneficial? Will it have a detrimental impact on the overall performance of your engine or not? 

Can I Mix Two Different Oil Brands in My Car? 

Well, yes, you can combine oil from different brands. Mixing oils of other brands will not have any major effect on your engine’s performance. However, it is not suggested that you mix oil from two distinct brands or different grades. 

Some experts believe that if two different types of oil have the same viscosity, they can be blended. However, the oils are specifically intended for specific types of engines, and mixing two lubricants can reduce the benefits of both oils to some amount.  

The oil additives are specifically developed to operate with the oil components, when added to other oil, it can decrease the functionality of the primary lubricant. Oil is a chemical combination. Each brand has its unique method of integrating these chemicals into the oil. The oil contains several compounds that promote lubrication, water resistance, and other properties. Some of these additives may negatively react with other additives in other oils.  

So, the oil will not deliver that fantastic performance when coupled with different brands or viscosity chemicals like zinc and is not suggested for the better overall condition of your car. 

When can I mix oil from different brands? 

It is not usually advisable to blend oil from different brands, but if an emergency arises, keep the following factors in mind. – 

Both oils should have the following characteristics:  

1. Same viscosity 

Oil viscosity determines how oil flows through the engine components at different temperatures. At high temperatures, high-viscosity oil performs better than low-viscosity oil. Using the incorrect viscosity oil can cause friction between engine components. So, before mixing the oils, make sure to verify their viscosity. 

2. Same API Rating 

The American Petroleum Institute (API) is a certification that assures engine oil is of high quality and meets industry standards. It is not advisable to blend high-rating oil with low-API-rating oil because this can reduce the overall benefits of the engine oil. SA, SB, SC, and SD are low-rated oils that can cause wear and tear on engine components, whereas SJ, SL, SM, and SN are high-rated oils. Mixing low API-rating oil with high API-rating oil can cause corrosion and wear and tear on engine components. 

FAQ’s on Mixing Oil Brands

If there is an emergency, you can mix a tiny amount of several types of oil. Adding 1 quart of 10W-40 oil to 4 quarts of 5W-30 should have no noticeable impact on your engine. We can say this because every time you add new oil to your engine, it is already blended with your old oil.

When you add new oil to your engine, it gets mixed with the old oil. Because when you flush the old oil from your engine, 10-15% of the oil remains in the engine components and is combined with the new oil.

Yes, you can combine synthetic and conventional oil. Synthetic blend oil, a mixture of fully synthetic and conventional oil, is used in modern vehicles. Synthetic blend oil protects your engine better than conventional oil and is less expensive than fully synthetic oil. However, it is advised to consult with your mechanic before using a mixed oil.

It is not suggested to mix Valvoline and Castrol oil since there may be different chemicals or additives in both oils that, when combined, can severely affect your engine component. If mixing them is the only alternative, be sure their viscosities are the same.

Blending Castrol MAGNATEC Stop-Start 5W-30 with Valvoline 5W-30 SynPower, for example, should not have a negative impact on your engine components.


Lastly, avoid combining oils from different brands. Some oils are meant for older engines, others for heavy-duty cars, and others for pure racing. Most modern engines will show no negative effect in the short term if you mix different oils. However, you may notice a drop in engine performance in the long run.  

If you wish to blend oil and have a choice, make sure you choose the same brand and viscosity of the oil. This is because different oils contain distinct chemical components that are designed to perform different tasks. Combining multiple chemicals increases the danger of engine damage and reduces engine performance. 

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