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What brake fluid does Subaru use?

Subaru generally uses DOT 3 or DOT 4 brake fluid depending on model and year; newer models commonly require DOT 4 for higher boiling points, but you should verify with the owner's manual or the reservoir cap labeling. Avoid DOT 5 silicone-based fluid unless specifically called for by Subaru.

Understanding the specification landscape

Because Subaru's lineup spans decades and regions, there isn't a single universal brake fluid type for all models. The exact specification is listed in the owner's manual and often printed on the reservoir cap. In most modern Subarus, DOT 4 is the standard; some older models may specify DOT 3.

Typical guidance observed across Subaru manuals includes the following:

Modern Subarus (late 2000s to present) commonly specify DOT 4 brake fluid because of its higher boiling point and moisture resistance, which improves braking performance in demanding conditions.

Some older Subarus or specific markets may list DOT 3; always confirm the specification for your exact model and year.

Conclusion: For most Subaru owners, DOT 4 is the recommended choice. Do not use DOT 5 silicone-based fluid unless the manual expressly allows it, and never mix fluids without guidance.

How to verify the correct brake fluid for your Subaru

To determine the exact specification for your vehicle, use these checks:

Inspect the reservoir cap or a label inside the engine bay for a DOT designation (for example, DOT 3 or DOT 4).

Consult the owner's manual under the fluids or maintenance section for the official specification.

Ask a Subaru dealer or a trusted service center if you’re unsure; provide your model, year, and VIN to get the correct recommendation.

Conclusion: When in doubt, select the DOT specification listed by Subaru for your model and year, and do not rely on generic guidance from another brand or older literature.

Practical maintenance and replacement guidance

These steps help ensure the brake system remains effective and free from moisture-related degradation:

Use the recommended DOT fluid (DOT 3, 4, or 5.1) and avoid DOT 5 silicone-based fluids unless explicitly specified by Subaru.

Brake fluid should be replaced at intervals suggested by Subaru, typically every 2–3 years, or when the fluid appears dark or contaminated.

When replacing: fully bleed and flush the system rather than simply topping up, to remove moisture-laden old fluid.

Conclusion: Regular verification of the correct specification and proper replacement intervals are essential for maintaining Subaru braking performance.

Summary

Subaru’s brake-fluid standard is most commonly DOT 4 for modern vehicles, with some older models using DOT 3. Always confirm the exact specification for your car via the owner's manual or reservoir cap. Do not use silicone-based DOT 5 unless Subaru explicitly allows it, and follow recommended maintenance intervals to keep brakes performing safely.

Is it okay to mix DOT 3 and dot 4 brake fluid?

Yes, you can mix DOT 3 and DOT 4 brake fluid, as they are chemically compatible, but you should never mix them with DOT 5. Mixing DOT 3 and DOT 4 is acceptable because both are glycol-based. Adding DOT 4 to DOT 3 will lower its boiling point, while adding DOT 3 to DOT 4 will lower its boiling point.
This video explains the differences between DOT 3 and DOT 4 brake fluid and whether they can be mixed: 1mHVAC Mechanic YouTube · Dec 28, 2021
Compatibility and mixing

DOT 3 and DOT 4: These are compatible and can be mixed without causing harm to the braking system.
DOT 3, 4, and 5.1: These are all compatible with each other and can be mixed.
DOT 5: This is silicone-based and is not compatible with DOT 3, DOT 4, or DOT 5.1. Mixing them will cause the system to fail.

What to consider when mixing

Boiling point: DOT 4 has a higher boiling point than DOT 3. Mixing them will lower the overall boiling point of the fluid in your system.
Performance: If your car requires DOT 4 and you mix it with DOT 3, you will reduce the braking system's performance.
Best practice: It is best to check your vehicle's manual and use the specific DOT fluid recommended for your car. If you need to upgrade to DOT 4, it is best to completely flush the old DOT 3 fluid out first to get the full benefits of the DOT 4 fluid.

This video explains what happens when you mix DOT 3 and DOT 4 brake fluids: 50sMotor MatchupsYouTube · Jan 2, 2024

What happens if I put DOT 3 instead of dot 4?

If you put DOT 3 brake fluid in a system that requires DOT 4, the main risk is reduced braking performance in high-heat situations because DOT 3 has a lower boiling point. While the fluids are compatible and mixing them is acceptable in a pinch, it's best to use the manufacturer-recommended fluid to ensure maximum brake safety, especially for high-performance or heavy-duty applications.
What happens

Lower boiling point: DOT 3 has a lower boiling point (205∘C205 raised to the composed with power cap C205∘𝐶 dry, 140∘C140 raised to the composed with power cap C140∘𝐶 wet) compared to DOT 4 (230∘C230 raised to the composed with power cap C230∘𝐶 dry, 155∘C155 raised to the composed with power cap C155∘𝐶 wet).
Potential for brake fade: In situations like descending a long, steep hill or aggressive driving, the brake fluid can get hot enough to boil. DOT 3 is more likely to reach its boiling point than DOT 4, which can cause a spongy brake pedal and loss of braking power (brake fade).
Incompatibility with DOT 5: DOT 3 is not compatible with silicone-based DOT 5 fluid. Never mix DOT 3, 4, or 5.1 with DOT 5 fluid, as this can damage the brake system.

What to do

Use the correct fluid: Always use the specific type of brake fluid recommended by your vehicle's manufacturer for safety and optimal performance.
If you mixed them: If you've accidentally mixed the two, it's not an immediate emergency for normal driving, but it's recommended to have the system flushed and refilled with the correct DOT 4 fluid. This will ensure you have the higher temperature safety margin that was originally specified for your car.
Wipe up spills: Brake fluid can damage paint. Be sure to wipe up any spills immediately.

Should I use DOT 3 or dot 4 brake fluid?

You should use the brake fluid type recommended in your vehicle's owner's manual or on the reservoir cap; however, you can use DOT 4 brake fluid in a system that calls for DOT 3 because DOT 4 has higher boiling points and can handle more heat. Do not use DOT 3 in a system that requires DOT 4, as it can compromise braking performance.
Use the fluid specified in your owner's manual

Check the cap or manual: The safest bet is to always use the type of brake fluid your vehicle's manufacturer recommends.
Do not mix: Never mix DOT 3 and DOT 4 with other types like DOT 5, as they are not compatible and can cause brake system failure.

When to consider upgrading to DOT 4

For high-performance vehicles: If your vehicle is used in high-temperature braking situations, like performance driving or racing, DOT 4 is a better choice due to its higher boiling points.
For hilly areas: If you frequently drive in hilly areas where you use your brakes often, DOT 4 is a good option.
For a small performance margin: Even for daily drivers, DOT 4 is often a better choice because it provides a larger safety margin as it absorbs moisture.

When DOT 3 is sufficient

Standard driving conditions: For typical daily driving, DOT 3 is perfectly adequate for most standard vehicles.

What brake fluid does a 2019 Subaru Outback take?

DOT 3 Brake Fluid: MAX Synthetic, Highest Grade, Superior Protection, 100k miles, 32 oz.

Kevin Bennett

Company Owner

Kevin Bennet is the founder and owner of Kevin's Autos, a leading automotive service provider in Australia. With a deep commitment to customer satisfaction and years of industry expertise, Kevin uses his blog to answer the most common questions posed by his customers. From maintenance tips to troubleshooting advice, Kevin's articles are designed to empower drivers with the knowledge they need to keep their vehicles running smoothly and safely.