2014-2018 Chevrolet Silverado Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

Every 2014-2018 Chevrolet Silverado takes DOT 3 brake fluid. GM's owner's manuals for this generation say the master cylinder reservoir is filled with DOT 3, and the 2016 and 2018 manuals say to replace the brake fluid every five years. If your truck is past that mark, or the fluid has never been changed, a full flush is due regardless of mileage.

What Fluid the 2014-2018 Silverado Uses

The spec is the same across this truck generation. We checked the 2014, 2016 and 2018 Silverado owner's manuals, and all three list DOT 3 hydraulic brake fluid for the brake system in the Recommended Fluids and Lubricants table. The GM part number printed for the fluid changes between years (the 2014 and 2016 books list 19299818, the 2018 book lists 19353126), but the requirement does not: DOT 3, from a clean, sealed container.

The 2015 and 2017 books were not part of our check, but they sit between two manuals that agree on DOT 3, so the fluid type is not in question. For the interval, the newer five-year guidance is the safer one to follow on any truck in this range, including a 2014. The manual also says to use only GM-approved DOT 3 and warns that the wrong or contaminated fluid can damage the brake system and lead to a loss of braking.

Can you use DOT 4 instead?

The federal brake fluid standard, FMVSS 116, sets higher minimum boiling points for DOT 4 than for DOT 3, and both are glycol-based fluids that the standard requires to be colorless to amber. DOT 4 is widely treated as compatible with DOT 3 systems, but GM specifies DOT 3 for this truck and that is what we recommend. What you must never add is DOT 5. DOT 5 is silicone-based (the standard requires it to be dyed purple) and it does not belong in a system designed for glycol fluid.

Why Brake Fluid Wears Out

Brake fluid does not get used up the way pads do. It goes bad from the inside. GM's own manual puts it plainly: brake fluid absorbs water over time, and it should be replaced at the specified interval to prevent increased stopping distance.

FMVSS 116 shows how much that moisture matters. It sets two boiling points for each grade: a dry figure for new fluid and a wet figure for fluid that has absorbed water.

That drop from 401 F to 284 F is the whole story. Brake & Front End magazine reports that DOT 3 fluid can pick up about 2 percent water in its first year and that just 3 percent water lowers its boiling point by about 100 F. When the fluid near a hot caliper boils, it turns into vapor, and vapor compresses. The pedal goes soft or sinks right when you need it, typically coming down a long grade or while towing.

Moisture is only half of it. The same article explains that heat breaks down the corrosion inhibitors in the fluid, and once they are spent, acids and sludge form that attack seals, caliper pistons and ABS valves. Copper leaches out of the brake lines into the fluid as this happens, which is why many shops test for copper content.

Signs Your Silverado Needs a Brake Fluid Flush

• It has been five years or more since the last flush, or you do not know when it was done.
• Dark fluid in the reservoir. New DOT 3 is colorless to amber. Fluid that looks brown or cloudy has aged.
• A soft or sinking pedal after hard use, such as towing, hauling or a long downhill run, that firms up again once the brakes cool.
• A failed test strip or meter reading. Brake & Front End notes the fluid should be replaced once copper content goes above 200 ppm.
• You are doing a brake job anyway. Opening the system to replace calipers, hoses or lines is the ideal time to flush.

A low reservoir is not a reason to flush, and it is not a reason to top off. The manual lists only two causes of a low level: normal pad wear, or a leak. As the pads wear, the caliper pistons move out and fluid follows them. GM tells owners not to top off, because the level comes back up when new pads push the pistons back in. If the level is below MIN and the pads are not worn, look for a leak. On these trucks a low level also turns on the brake warning light, and the 2016 manual describes a BRAKE FLUID LOW message as well.

How to Flush Brake Fluid on a 2014-2018 Silverado

A flush is not hard, but it rewards patience. Here is how it goes:

1. Clean the reservoir cap and the area around it before you open it. GM calls for this so dirt cannot get into the system.
2. Pull most of the old fluid out of the reservoir and refill with fresh DOT 3 from a sealed container.
3. Bleed each wheel in the sequence the factory service information gives, until clean fluid comes out of every bleeder. Keep the reservoir from running low while you work so you do not pull air into the lines.
4. Handle the ABS unit correctly. A normal flush pushes fresh fluid through the ABS modulator. If air has gotten into the modulator, for example because the reservoir ran dry, the solenoids may need to be cycled with a scan tool to purge it.
5. Set the final level above MIN and below MAX, then check pedal feel before you drive.

Wash off any spilled fluid right away, since brake fluid damages paint. Keep your fluid container tightly capped: federal labeling rules require every bottle to warn that the container must stay clean and tightly closed so the fluid does not absorb moisture. A half-used bottle that has been sitting open in the garage is not new fluid anymore.

Tighten bleeder screws to the value in the factory service manual. They are small and easy to snap if you overdo it.

What to Replace at the Same Time

A flush is a good time to look over the whole hydraulic system. While each wheel is open:

• Check the pads and rotors. If the pads are near the end, do them first and then flush, since pushing the pistons back changes the reservoir level. Our 2014-2018 Silverado 1500 front brake pads and rotors kit covers the front axle in one box, and you can browse more brake pads and brake rotors for the rear.
• Inspect the rubber hoses for cracking, bulging or seepage at the crimps. Old fluid is hard on hoses. See our brake hoses.
• Watch the calipers. A stuck piston or a bleeder that will not open usually means corrosion inside. Replacement brake calipers are worth fitting before you pour fresh fluid through them.
• Check the steel lines for rust along the frame, a common problem on trucks in salt states. We carry brake lines too.

How Hard Is the Job?

For someone who has already done a pad job, a Silverado brake flush is a moderate driveway job. It takes a helper or a one-person bleeder kit, jack stands, a wrench that fits the bleeders, and enough sealed DOT 3 to push clean fluid through all four corners. The two ways to get it wrong are letting the reservoir run dry (air in the ABS unit can mean a scan tool or a shop visit) and using old or wrong fluid. If the pedal is still soft after bleeding, stop and get the system checked before you drive the truck.

Frequently Asked Questions

What brake fluid does a 2014-2018 Silverado take?

DOT 3. The 2014, 2016 and 2018 owner's manuals all list DOT 3 hydraulic brake fluid for the brake system, from a clean, sealed container.

How often should I change the brake fluid on my Silverado?

The 2016 and 2018 owner's manuals say to replace the brake fluid every five years. Trucks that tow a lot or live in humid climates can benefit from testing the fluid sooner.

Can I mix DOT 3 and DOT 4 in my Silverado?

Both are glycol-based and DOT 4 is widely treated as compatible, but GM specifies DOT 3 for this truck. Stick with DOT 3 and never add silicone DOT 5.

Should I top off the brake fluid when it is low?

No. GM says not to top off. The level falls as the pads wear and comes back up when new pads are installed. A level below MIN with good pads points to a leak that needs repair.

Why does my pedal go soft when towing down a hill?

One common cause is old fluid that has absorbed water and boils at a lower temperature. Fresh DOT 3 has a much higher boiling point than moisture-laden fluid. Overheated pads and rotors can also cause fade, so check both.

Is a brake flush needed when I replace pads?

It is not required, but it is a good time to do one if the fluid is old. It is strongly recommended any time you replace a caliper, hose or line.

Sources

1. 2016 Chevrolet Silverado Owner's Manual (GM) - DOT 3 spec, five-year replacement interval, do-not-top-off guidance, BRAKE FLUID LOW message, moisture warning
2. 2018 Chevrolet Silverado Owner's Manual (GM) - DOT 3 spec, five-year replacement interval, GM part number 19353126
3. 2014 Chevrolet Silverado Owner's Manual (GM) - DOT 3 spec, GM part number 19299818, 10-year footnote, paint damage caution
4. 49 CFR 571.116, FMVSS No. 116 Motor Vehicle Brake Fluids - dry and wet boiling points, fluid color, container moisture warning
5. Brake & Front End: Brake Fluid Testing, Bleeding and Flushing - moisture uptake, boiling point loss, corrosion inhibitors, 200 ppm copper threshold, ABS bleeding