Car Brake Fluid & Clutch Fluid
Car Brake Fluid & Clutch Fluid Products
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Car Brake Fluid & Clutch Fluid
Brake Fluid and Clutch Fluid for all Makes & Models
Shop at Opie Oils for a great choice of brake and clutch fluid, at fantastic prices. Get your brake fluid order delivered to your home, workplace, or garage.
What is brake fluid?
Brake fluid is usually made from a synthetic or mineral-based formula. It is essential to your braking system and therefore, your safety. The fluid transfers hydraulic pressure from the brake master cylinder to your brakes, allowing you to control your stopping speed when driving.
What is brake fluid used for?
Brake fluid is essential for cars, vans, motorcycles, and even some bicycles with hydraulic brakes. It can also be used as clutch fluid, which is essential for manual transmission vehicles. For the vast majority of cars, a single fluid is used in both the clutch and brake reservoirs. Check the cap of your clutch fluid reservoir – it should indicate if you need a special hydraulic fluid.
What are the different types of brake fluid?
The three main types of brake fluid available are Dot 3, Dot 4 and Dot 5.1. There is also an unofficially rated brake fluid – ‘Super’ Dot 4 – which is used for racing and performance cars, and a specialist silicon-based fluid called (confusingly) Dot 5.
Dot 3, Dot 4, and Dot 5.1 are glycol-based fluids. Dot 5 (silicon) fluid is not used in passenger cars - it’s used in some off-road military vehicles, for instance - and because of its different viscosity and composition, it isn’t compatible with the other fluids, and can’t be substituted in place of them.
Brake fluid boiling points
Another crucial brake fluid characteristic is its boiling point. Dot manufacturers are required to meet specific criteria relating to a fluid’s minimum dry and wet boiling points. These boiling points indicate the minimum temperature a brake fluid can perform at before the brake fluid starts to boil – which can lead to brake failure.
See below for the minimum boiling points of Dot brake fluids.
Minimum boiling points by brake fluid type
| Brake Fluid | Dry Boiling Point | Wet Boiling Point |
|---|---|---|
| Dot 3 | 205 °C (401 °F) | 140 °C (284 °F) |
| Dot 4 | 230 °C (446 °F) | 155 °C (311 °F) |
| Dot 5 | 260 °C (518 °F) | 180 °C (356 °F) |
| Dot 5.1 | 270 °C (518 °F) | 190 °C (374 °F¬) |
Remember, these are only the minimum standards. Brake fluid manufacturers often improve these figures, and it is possible to find Dot 4 brake fluid with a higher boiling point than some Dot 5.1 fluids.
Dot 3, Dot 4 and Dot 5.1 brake fluids are compatible with each other as they are all glycol-based brake fluids, so you can mix them without harming your brake system. Remember, it is crucial to never confuse Dot 5.1 (glycol-based) with Dot 5, which is silicone-based and should never be mixed with any other Dot fluid.
Why do different brake fluids exist?
As a critical safety aspect for all vehicles, the integrity of the braking system is non-negotiable. High-performance brake fluids are an integral part of a vehicle's effective and safe braking. Modern cars have the ability to self-stabilise by detecting and reducing traction loss, providing an optimised response. Moreover, heavier vehicles require braking fluid with higher boiling points to avoid vaporising in the system. Therefore, Dot 3 and Dot 4 brake fluids are no longer sufficient for the general market.
When should I change brake fluid?
Manufacturers recommend changing the brake fluid every 1 to 2 years because as brake fluid gets older, it continues to absorb more water which decreases its boiling point to dangerous levels. Water-contaminated brake fluid causes vapour bubbles to develop, which eventually applies force to the brake pedal, making your brakes feel spongy.
Why choose Opie Oils?
We've got a vast selection of brake fluids from several leading brands, as well as more affordable options. Suitable for a variety of different cars, you can rest assured that we'll have something ideal for you.
Dot 3, Dot 4, and Dot 5.1 are all available to purchase online, as well as 'Super’ Dot 4 - a brake fluid used for racing competitions.
You can find which kind of brake fluid your vehicle requires in your vehicle handbook. However if you're not sure, or you have a unique or race vehicle, contact the Opie Oils experts for brake fluid and clutch fluid advice.
