How to Check Brake Fluid
Learn how to check your brake fluid level safely. Quick 5-minute check that's essential for your safety on the road.
⚠️ Critical Safety Information
- • Brake fluid is TOXIC and corrosive - avoid skin contact and DO NOT drink
- • Wipe up spills immediately - it damages paint and rubber
- • If brake fluid is very low or drops quickly, DO NOT drive - call a mechanic
- • Use only the correct brake fluid type specified in your handbook
- • Keep brake fluid away from eyes - seek medical help if contact occurs
Why Check Brake Fluid?
Brake fluid is essential for your car's braking system. When you press the brake pedal, brake fluid transmits that pressure to your brakes to stop the car.
- Essential for safety: Low fluid = reduced braking power or brake failure
- Early warning: Low fluid can indicate brake wear or leaks
- MOT requirement: Brake system must work effectively
What You'll Need
- Your car's handbook - to identify the brake fluid reservoir
- Clean cloth - if you need to wipe the reservoir to see level
- Good lighting - to see the level clearly
Step-by-Step Instructions
1. Park on Level Ground
Park on flat, level ground. Turn off the engine and allow it to cool for a few minutes if you've just been driving. The engine bay will be hot.
2. Open the Bonnet
Pull the bonnet release lever inside your car (usually under the dashboard on the driver's side). Then release the safety catch under the bonnet and prop it open.
3. Locate the Brake Fluid Reservoir
Look for a small translucent plastic reservoir, usually on the driver's side near the back of the engine bay, close to the bulkhead. It will have brake fluid warning symbols on the cap.
- The cap is usually round and black or yellow
- It may say "BRAKE FLUID" or have a brake warning symbol
- Check your handbook if you're not sure which one it is
⚠️ DON'T confuse it with the coolant reservoir or power steering fluid!
4. Check the Fluid Level
Most brake fluid reservoirs are translucent, so you can see the level without opening the cap. Look for the MIN and MAX markings on the side.
- Above MIN mark: Level is acceptable
- Between MIN and MAX: Perfect level
- At or below MIN: Needs topping up OR brake pads are worn
Tip: Wipe the reservoir with a clean cloth if it's dirty and you can't see the level clearly.
5. Check the Fluid Condition
While checking the level, look at the color of the brake fluid:
- Light golden or clear: Good condition
- Dark brown or black: Old - should be changed
- Cloudy or murky: Contaminated - see a mechanic
Should You Top Up?
Before topping up brake fluid, read this:
- • Brake fluid level drops slightly as brake pads wear - this is NORMAL
- • If fluid is just below MAX but above MIN, this is fine
- • Only top up if it's at or close to the MIN mark
- • If fluid drops quickly or is well below MIN, you may have a leak - see a mechanic immediately
- • When you get new brake pads fitted, the garage will top up the fluid as part of the service
How to Top Up Brake Fluid (If Needed)
⚠️ Important: Only top up if fluid is at or below MIN. Use the correct fluid type specified in your handbook (DOT 3, DOT 4, or DOT 5.1). NEVER mix different types.
- 1. Clean the reservoir cap to prevent dirt falling in
- 2. Carefully unscrew the cap (may have clips to release first)
- 3. Pour fluid slowly to the MAX mark - don't overfill
- 4. Replace the cap securely
- 5. Wipe up any spills immediately with a damp cloth
If you're not confident topping up yourself, any garage will do this for you quickly and cheaply.
Brake Fluid Types
| Type | Used In | Notes |
|---|---|---|
| DOT 3 | Older cars | Lower boiling point |
| DOT 4 | Most modern cars | Most common type |
| DOT 5.1 | Performance cars | Higher boiling point |
⚠️ Always check your owner's manual for the correct type. Never use DOT 5 (silicone-based) in a car that requires DOT 3/4/5.1.
⚠️ See a Mechanic Immediately If:
- • Brake fluid level is very low or drops quickly
- • Brake warning light comes on
- • Brake pedal feels spongy or goes to the floor
- • You see fluid puddles under the car
- • Brakes feel less effective than usual
- • Grinding or squealing noises when braking
DO NOT drive if you suspect a brake problem!
Track Your Brake Maintenance
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