2012-2013 Buick Regal Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2012-2013 Buick Regal uses glycol-based brake fluid, either DOT 3 or DOT 4, and the correct one is printed on the reservoir cap. GM's owner manual says that if the cap calls for DOT 4, the brake/clutch hydraulic system should be flushed and refilled with new DOT 4 fluid every two years. If your cap says DOT 3, use only new DOT 3 from a sealed container, and have the fluid condition checked at every brake inspection.

Which Brake Fluid Does the 2012-2013 Regal Take?

GM built this generation of Regal with a reservoir that may be filled with either of two fluid grades, so the car tells you which one it has. The owner manual states that the master cylinder reservoir is filled with DOT 3 or DOT 4 brake fluid as indicated on the reservoir cap. Before you buy fluid, open the hood, find the brake reservoir on the master cylinder, and read the cap. Do not guess from the trim level.

The manual's Recommended Fluids table lists GM part numbers for both grades:

On manual-transmission Regals, the clutch hydraulic system shares this same reservoir, so the fluid you put in serves both the brakes and the clutch. That is one more reason to use the exact grade on the cap and to bleed the clutch circuit when you flush the brakes.

Whatever brand you choose, it should be new fluid from a sealed container. GM is explicit on that point, because an opened bottle absorbs moisture from the air while it sits on a shelf.

How Often to Flush: The GM Interval

The 2012 Regal maintenance schedule lists a Special Application Service for vehicles using DOT 4 brake fluid only: change the brake/clutch hydraulic fluid every two years. The Vehicle Care section repeats it, recommending that the system be flushed and refilled with new DOT 4 fluid at a regular maintenance service every two years.

For cars with DOT 3 on the cap, the schedule does not print a fixed replacement interval. It calls for the brake system to be inspected at the regular 7,500-mile service. In practice, that inspection is the time to have the fluid tested. A Regal that is more than ten years old and has never had its fluid changed is due, regardless of which grade it uses.

The two-year figure is a time interval, not a mileage one. A Regal that sits in a garage and rarely gets driven still needs the flush, because the fluid ages from moisture exposure whether the car moves or not.

Why Brake Fluid Wears Out

DOT 3 and DOT 4 are glycol-based fluids, and glycol fluids are hygroscopic: they pull moisture out of the air through hoses, seals and the reservoir vent. Water lowers the fluid's boiling point. Federal Motor Vehicle Safety Standard 116 sets minimum boiling points for new (dry) fluid and for fluid that has absorbed water (wet):

ADVICS, a brake system supplier, explains that the wet boiling point is measured with 3.7 percent water by volume, and that fluid in service typically reaches that level in roughly two years for DOT 4 and one year for DOT 3. When hot brakes push the fluid past its boiling point, vapor bubbles form in the lines. Vapor compresses where liquid does not, which shows up as a spongy or sinking pedal and, in the worst case, loss of braking.

Moisture also attacks metal. Brake and Front End magazine notes that rising copper content in used fluid is a sign that corrosion may be occurring inside the system. On a Regal, that means the ABS hydraulic unit, the master cylinder bore and the caliper pistons, all of which cost far more than a bottle of fluid.

Signs Your Regal Needs a Brake Fluid Service

• Fluid is dark or cloudy. New fluid is clear to light amber. Dark fluid has picked up moisture and contamination.
• Spongy or low pedal, especially after repeated hard stops or a long downhill. The owner manual says to see a technician if the pedal does not return to normal height or if pedal travel increases rapidly.
• BRAKE FLUID LOW message on the Driver Information Center, or the brake warning light. The manual gives only two reasons for a dropping level: normal lining wear, or a leak.
• Test strip or tester reading showing high moisture or copper content at an inspection.
• Two years since the last flush on a DOT 4 car, or no record of a flush at all.

Note what GM says about topping off: do not do it. As the pads wear, the caliper pistons move out and the reservoir level drops. If you add fluid then, there will be too much when new pads push the pistons back. Add or remove fluid only when brake or clutch hydraulic work is done, and keep the level above MIN and not over MAX. If the level is low and the pads are not worn, look for a leak. Adding fluid will not fix one.

Doing the Flush: What to Know Before You Start

A brake fluid flush on this car is a moderate DIY job for someone who has bled brakes before. A few Regal-specific points:

• Four-wheel disc brakes. The manual confirms the Regal has disc brakes, so there are four caliper bleeders to service, plus the clutch circuit on manual-transmission cars.
• Electric parking brake. This generation uses an electric parking brake. If you remove rear calipers or push rear pistons back during pad work, follow the factory service procedure for the electric parking brake so you do not damage the actuators. A fluid flush alone does not require retracting the pistons.
• ABS unit. Fluid in the ABS modulator does not always exchange fully with a basic bleed. Follow the bleed sequence and any scan-tool bleed step in the factory service information for your VIN.
• Clean the cap first. GM advises cleaning the cap and the area around it before removing it so dirt does not fall into the reservoir.
• Protect the paint. Brake fluid damages painted surfaces. Wash off any spill immediately.
• Never introduce petroleum. GM warns that just a few drops of mineral-based oil, such as engine oil, can damage brake hydraulic parts badly enough that they must be replaced. Use a clean catch bottle and a dedicated funnel.

Buy enough sealed fluid to push clean fluid out of every bleeder, with extra if the clutch circuit is included, and never reuse what you catch.

Replace at the Same Time: Pads, Rotors and Hardware

A fluid flush is a good moment to inspect the rest of the system, since the wheels are already off. GM recommends inspecting the pads at every tire rotation and replacing linings as complete axle sets. The pads have built-in wear indicators that make a high-pitched sound when they are worn.

If the front brakes are due, the Brembo OE front disc brake kit for the 2012-2013 Buick Regal pairs coated rotors with ceramic pads. Owners of a 2012 Regal with Brembo front calipers who want a sportier setup can look at the Hawk Talon drilled and slotted front rotor set for the 2012 Regal with Brembo calipers. For separate components, browse our brake pads, brake rotors and brake hardware kits. If a flexible line is cracked or swollen, see our brake hoses.

GM also cautions that installing the wrong pads can upset the balance between front and rear braking, so buy parts matched to your exact brake package.

Frequently Asked Questions

Is the 2012-2013 Buick Regal DOT 3 or DOT 4?

It can be either. GM's owner manual says the reservoir is filled with DOT 3 or DOT 4 as indicated on the reservoir cap. Read the cap on your car and use that grade.

How often should I change brake fluid on a Regal?

For DOT 4 cars, GM recommends a flush and refill every two years. For DOT 3 cars, have the fluid checked at each brake inspection and replace it when testing shows moisture or corrosion, or if there is no record of a change.

Can I put DOT 4 in a Regal that says DOT 3?

DOT 3, DOT 4 and DOT 5.1 are all glycol-based and compatible with each other, according to Brake and Front End magazine. GM's instruction, however, is to use the grade marked on the cap, and that is the safest choice. Never use DOT 5 silicone fluid, which does not mix with glycol fluid.

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

GM says no. The level drops normally as pads wear, and topping off leaves too much fluid when new pads are installed. If the level is low and the pads are not worn, have the system checked for a leak.

Does a brake fluid flush also cover the clutch?

On manual-transmission Regals, the brakes and clutch share one reservoir, so the clutch hydraulic circuit uses the same fluid and should be bled along with the brakes.

Sources

1. 2012 Buick Regal Owner Manual, Checking Brake Fluid (ManualsLib) - DOT 3 or DOT 4 per cap, sealed container, DOT 4 flush every two years
2. 2012 Buick Regal Owner Manual (full PDF) - GM fluid part numbers, maintenance schedule, shared clutch reservoir, electric parking brake, disc brakes, topping-off and petroleum warnings
3. 49 CFR 571.116, FMVSS 116 Motor Vehicle Brake Fluids (Cornell LII) - DOT 3 and DOT 4 dry and wet minimum boiling points
4. ADVICS: Brake Fluid Boiling Points - wet boiling point at 3.7 percent water, typical time to reach it, vapor lock
5. Brake and Front End: Brake Fluid DOT 3, 4, 5 and 5.1 FAQ - glycol fluid compatibility, DOT 5 incompatibility, copper as a corrosion indicator