Brake fluids
Varieties of brake fluids: which one to choose?
In modern cars, manufacturers use one of two braking systems - pneumatic or hydraulic. The second type is mainly put on passenger cars. For the system to work effectively, on average, once every 2-3 years, it is necessary to change the fluid in it, which is responsible for braking the car.
Now there are four popular brake fluid types on the market that correspond to the American Department Of Transportation classification – DOT 4, DOT 4 LV, DOT 5 and DOT 5.1. However, how do they differ and which one to choose for your car?
Key points about brake fluid
Brake fluid is the substance used in the hydraulic brake system. It transfers pressure from the master brake cylinder to the working wheel brake cylinders. The efficiency of the entire system is affected by 5 main characteristics of the product:
HIGH BOILING POINT
LOW TEMPERATURE FOR SOLIDIFICATION
ANTI-CORROSION AND LUBRICATING PROPERTIES
HIGH BOILING POINT
LOW TEMPERATURE FOR SOLIDIFICATION
ANTI-CORROSION AND LUBRICATING PROPERTIES
LOW ABILITY TO ABSORB MOISTURE
CHEMICAL NEUTRALITY TO RUBBER PARTS
LOW ABILITY TO ABSORB MOISTURE
CHEMICAL NEUTRALITY TO RUBBER PARTS
We compared four popular products
on main criteria to help you decide:
| DOT 4 | DOT 4 LV | DOT 5 | DOT 5.1 | |
| Boiling point (dry) | 230 °C | 265 °C | 260 °C | 260 °C |
| Boiling point (wet) | 155 °C | 170 °C | 180 °C | 180 °C |
| Max viscosity | 1800 | 700 | 900 | 900 |
| Type |
on polyglycol basis |
on polyglycol basis | on silicone basis | on polyglycol basis |
There is also DOT 3 on the market, but this product is not suitable for many modern cars.
DOT 5 preceded DOT 5.1. It differs in type - it is based on silicone, not polyglycol. Thanks to this technology, the substance can be changed every 5 years, but it is more expensive and does not surpass analogues in terms of characteristics.
DOT 4 LV is considered optimal.
Unlike the other products, this fluid has a lower viscosity, which allows for faster pressure build up and down, which in turn provides improved brake response (prevents brake fade).
Benefits:
- special low-viscosity formula for ABS, ASC, ESP, ESC and EBD systems
- prevents brake fade, exceeds DOT 4 requirements and the newest ISO 4925 Class 6 norm
- superior wet boiling point
Benefits:
- ABS compatible
- prevents brake fade and exceeds DOT 4 standard requirements
- protects against performance decline due to water absorption
Brake fluid replacement tips
For your convenience, we have also collected some basic tips for changing the brake fluid in the system:
- Replace brake fluid every two years.
- Never mix brake fluids of different types.
- In cars since 2007, we recommend using DOT 4 LV brake fluid, although this is not always clearly stated by the car manufacturer.
- DOT 4 LV may be used if DOT 4 is recommended.