can you mix gear oil brands

The question of whether you can mix gear oil brands is a commonly asked one among vehicle owners and enthusiasts. The answer is not a simple yes or no, as it depends on various factors such as the compatibility of the oils, the specifications set by the manufacturers, and the type of gear system being used. Let’s delve into this topic and explore the intricacies of mixing gear oil brands.

Understanding Gear Oil Types

Before we discuss whether you can mix gear oil brands, it’s important to understand the different types of gear oil available. Gear oils come in various viscosities and are formulated with specific additives to suit different gear systems. Here are some common gear oil types:

  • GL-4: Designed for manual transmissions and provides standard protection.
  • GL-5: Suitable for differentials and offers enhanced protection against extreme pressure and temperature.
  • MTF: Specifically for manual transmissions, offering improved fuel efficiency and smoother gear shifts.
  • Synthetic Gear Oil: Provides superior performance, increased lubrication, and better resistance to breakdown.

Factors to Consider

When contemplating mixing gear oil brands, several factors need to be taken into consideration to ensure a safe and optimal outcome. Here are some important points:

  1. Oil Compatibility: Check the compatibility between the oils you intend to mix. Mixing incompatible gear oils can lead to chemical reactions and ultimately damage your gear system.
  2. Manufacturer’s Specifications: Review the manufacturer’s recommendations regarding the use of specific gear oils. Some manufacturers may prohibit the mixing of different brands or types of gear oil to maintain warranty coverage.
  3. Viscosity: Ensure that the viscosities of the oils you plan to mix are similar. Mixing oils with significantly different viscosities can result in poor lubrication and compromised performance.
  4. Additive Packages: Compare the additive packages of the oils to be mixed. Different brands may use different additives, and mixing incompatible additives can lead to reduced performance or oil breakdown.

Table: Compatibility Chart

Gear Oil Brand/TypeBrand X GL-4Brand Y GL-5Brand Z Synthetic
Brand X GL-4
Brand Y GL-5
Brand Z Synthetic

Note: The table above illustrates the compatibility between different brands/types of gear oils. “✔” indicates compatibility, while “✖” indicates incompatibility.

Potential Risks of Mixing Gear Oil Brands

Although it may be tempting to mix gear oil brands to create a blend that suits your preferences or to use up leftover oil, it’s essential to acknowledge the potential risks involved. Here are some risks you may encounter when mixing gear oil brands:

  • Reduced Lubrication: Mixing incompatible gear oils can result in diminished lubrication properties, leading to increased wear and tear on gear components.
  • Chemical Reactions: Some gear oils may contain additives or base oils that are not compatible with each other. Mixing these oils can cause chemical reactions, resulting in oil breakdown and reduced performance.
  • Warranty Void: Mixing gear oils against the manufacturer’s recommendations may void your warranty, leaving you responsible for repair or replacement costs in case of damage.

Best Practice: Stick to a Single Brand

Considering the potential risks involved, it is generally recommended to stick to a single brand and type of gear oil as specified by the vehicle manufacturer. Using a high-quality oil that meets the manufacturer’s specifications ensures optimal performance and protection for your gear system. It’s better to err on the side of caution and avoid mixing gear oil brands unless explicitly stated to be compatible.


While it may seem tempting to mix gear oil brands, the potential risks and compatibility concerns make it generally advisable to avoid doing so. Following the manufacturer’s recommendations and using a high-quality gear oil specifically formulated for your gear system ensures optimal performance and longevity. When it comes to gear oil, it’s often best to play it safe and stick to a single brand.