Low brake fluid levels mean the brakes will work badly or fail. If you check levels on a regular basis, you'll know if there's a leak. The fluid level does fall as the brake pads and shoes wear, but if you’re topping up regularly, means there's a leak so take the car off the road until it's fixed. Check brake fluid levels once a week, or before a long journey. The fluid should be renewed once a year, no matter how far you've driven.

1. Make sure the car is parked on a level surface, and wipe the brake fluid reservoir clean. The level should be between the “max” and “min” marks.
2. To top up, unscrew the reservoir cap. The inside of the cap often fits down into the fluid, so take it off slowly, placing on a piece of clean cloth to catch drips.
3. Top up to the max mark. Use a good quality brake fluid which meets the standard DOT 4 (it should be marked on the container). You should use new fluid from a freshly opened container.
4. Replace the reservoir cap, screw it in and throw away the cloth.