Valvoline DOT3/4 is good brake fluid. Been using it in my trikes brake and clutch unit for about 8 years. All brake fluid is synthetic because its glycol based. The one you have to watch out for is DOT 5 because it is silicone based and will not mix with the others.
Different types of Brake Fluid
There are various types and no. of specifications are available in the world, like FMVSS 116- DOT3, DOT4, DOT5, DOT5.1; SAE-J1703, J1704, J1705; ISO-4025, JIS-K-2233 etc; and OEM also made own specification. Every car owner wants to know about the difference of various types of brake fluid.
Basically there are two type of brake fluids (1) Petroleum (mineral oil) base (2) Non petroleum base. As petroleum base brake fluid is rarely used in automobile industry. Non- petroleum based brake fluid is widely used by the industry. FMVSS-116 brake fluid specification is based upon non- petroleum products and this specification is universal accepted brake fluid specification, so it is better for us to know the difference between the brake fluids in this specification. First of all, it's important to understand the chemical nature of brake fluid. DOT 3, DOT4, DOT5.1 brake fluids are the mixtures of glycols and glycol ethers. DOT 5 is silicone base
The main differences in the brake fluid are as per below :-
1) Boiling point(ERBP)
BRAKE FLUID |
MINIMUM BOILING POINT (ERBP) SPECIFICATION |
|
DRY |
WET |
DOT 3 |
205 Deg C |
140 Deg C |
DOT 4 |
230 Deg C |
155 Deg C |
DOT 5 |
260 Deg C |
180 Deg C |
DOT 5.1 |
260 Deg C |
180 Deg C |
2) Viscosity
Kinematic viscosity: All brake fluids (DOT 3, DOT 4, DOT 5 & DOT 5.1) must meet a minimum viscosity test of not less than 1.5 centistokes at 100° C and must not be more than the following to meet their various classifications.
BRAKE FLUID |
MAXIMUM VISCOSITY
AT MINUS 40 Deg C |
DOT 3 |
1500 cst |
DOT 4 |
1800 cst |
DOT 5 |
900 cst |
DOT 5.1 |
900 cst |
(3) Color:
The Brake Fluids are available in various colours like Brake Fluid DOT 3 is available in clear, Pale Yellow, Blue & Crimson Red colour, similarly brake fluid DOT 4 is available in Clear, Pale Yellow & Crimson Red colour, brake fluid DOT 5.1 is available Clear, Pale Yellow & Blue colour. Brake Fluid DOT 5 is available in Purple & Violet colour so colour is not a criteria to distinguish between the different types of brake fluids. The color is added in brake fluid to detect the leakage easily and color does not effect the quality of brake fluid.
DOT 3: This brake fluid is a poly glycol base product. Its dry boiling point (ERBP) is 205°C minimum and wet boiling point (Wet ERBP) is 140°C minimum. It absorbs 1 to 2 percent of water per year depending on climate and operating conditions. It is used in most domestic cars and light trucks in normal driving. This brake fluid does not require cleaning the system and can be mixed with DOT 4 and DOT 5.1 without damage the system. This brake fluid absorbs moisture from the atmosphere thus reduces its boiling point (ERBP). It can also damage the paint on a vehicle.
DOT 4:This brake fluid is also based upon poly glycol. Its dry boiling point (ERBP) is 230°C minimum and wet boiling point (Wet ERBP) is 155°C minimum. It is used in medium and higher size of modern cars; and also for vehicles in high-altitude, towing, high-speed braking situations or ABS systems. This brake fluid does not require cleaning the system and it can be mixed with DOT 3,DOT 5.1 without damage to the system. This brake fluid also absorbs moisture out of the atmosphere thus reduces its boiling point (ERBP). It can also damage the paint on a vehicle. The modified poly glycol boric ester DOT4 brake fluid is also available.
DOT 5: This brake fluid is based upon silicone. Its dry boiling point (ERBP) is 260°C minimum and wet boiling point is (Wet ERBP) 180°C. It is used in applications, like for weekend, antique, collector cars that sit for long periods and for some military vehicles. Some car manufacturers are also used in their road driven vehicles. This brake fluid does not mix with DOT 3, DOT 4 or DOT 5.1. It will not absorb water and will not damage the paint on a vehicle. It is also compatible with most rubber formulations. It absorbs more air and giving poor pedal feeling. It is unsuitable for racing due to more compressibility under high temperatures. If as little as one drop of water enters the fluid, severe localized corrosion, freezing or gassing may occur. This can happen because water is heavier and not mixable with silicone fluids thus it is unsuitable for ABS.
DOT 5 fluid is highly compressible due to aeration and foaming under normal braking conditions, providing a spongy brake feel. Poly glycol type fluids are 2 times less compressible than silicone type fluids, even when heated.
DOT 5.1: This brake fluid is also based upon poly glycol. Its dry boiling point (ERBP) is 260°C minimum and wet boiling point (Wet ERBP) is 180°C minimum. It is used in severe-duty vehicles such as fleets and delivery trucks; towing vehicles, and racecars. It can be mixed with DOT 3 or DOT 4 without damage to the system. It maintains higher boiling point than DOT 3 or DOT 4 fluids. It is excellent for severe duty applications particularly for racing of car. It also absorbs moisture out of the atmosphere and thus reduces its boiling point. It can also damage the paint on a vehicle.