2017-2019 Buick Lacrosse Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2017-2019 Buick LaCrosse uses GM approved DOT 3 brake fluid, and GM's maintenance schedule calls for replacing it every five years. Only add fluid from a clean, sealed container, and only when work has been done on the hydraulic system - a dropping reservoir is a sign of pad wear or a leak, not a reason to top off.

What brake fluid the LaCrosse takes

The owner's manual for this generation of LaCrosse states that the brake master cylinder reservoir is filled with GM approved DOT 3 brake fluid, and that the required type is marked on the reservoir cap. The Recommended Fluids and Lubricants table lists DOT 3 Hydraulic Brake Fluid, GM part number 19299818 (19299819 in Canada), for the hydraulic brake system. On a 2018 or 2019 car, read the reservoir cap before you buy fluid - the cap is GM's own label for what belongs in that system.

DOT 3 is a federal standard, not a brand. Under Federal Motor Vehicle Safety Standard 116, every fluid sold as DOT 3 must meet minimum boiling points, and every container must carry the warning to keep the fluid clean and dry because contamination with dirt, water or petroleum products can cause brake failure. That is why GM tells owners to use fluid only from a sealed container: an opened bottle that has sat on a shelf has been pulling moisture out of the air.

Flush interval: every five years

In the LaCrosse maintenance schedule, the footnote on brake fluid is short: replace brake fluid every five years. It is a time interval, not a mileage one, because the fluid ages whether the car is driven or not. The manual explains why - brake fluid absorbs water over time, which degrades its effectiveness, and GM says to replace it at the specified interval to prevent increased stopping distance.

The same schedule has the brake system inspected at regular service visits, along with a check of the parking brake and the transmission park mechanism. Use those visits to look at the fluid color and level. A shop can also test the fluid's moisture content or boiling point; if the test fails, flush it early rather than waiting for the five-year mark.

How fast does fluid pick up water? ADVICS, an OE brake supplier, explains that glycol-ether brake fluid is hygroscopic, and that the wet boiling point is measured once the fluid has absorbed 3.7 percent water by volume. Compare the dry and wet columns in the table above: DOT 3 loses more than 100 degrees Fahrenheit of boiling-point margin between fresh and saturated. Boiled fluid makes vapor bubbles, and vapor compresses - that is the soft, sinking pedal you feel after a long downhill stop on old fluid. ADVICS also stresses that the replacement schedule should come from the owner's manual, which for this car means the five-year interval.

Checking the level the right way

Park on level ground in P. The fluid should sit between the minimum and maximum marks on the reservoir, which is shown in the engine compartment overview of the manual. GM lists only two reasons the level drops:

• Normal pad wear. As the pads get thinner, the caliper pistons move out and fluid follows them. When new pads go on, the level comes back up.
• A leak in the hydraulic system. A leak means the brakes will not work well, and adding fluid does not fix it.

That is why GM says not to top off brake fluid. If you fill a reservoir that is low from worn pads, it will overflow when the pistons are pushed back for a pad change. GM also warns that overfilled fluid can spill onto a hot engine and burn, and that brake fluid damages paint - wash any spill off right away. Always clean the cap and the area around it before opening the reservoir so dirt does not fall in.

Warning lights and messages tied to fluid

The LaCrosse brake system uses two hydraulic circuits, so if one fails the other can still stop the car, but not with normal performance. When the fluid falls low, the red brake system warning light comes on and the Driver Information Center can show BRAKE FLUID LOW. GM's instruction if the light stays on after you have pulled over and stopped is to have the car towed for service.

This generation also has an Electric Parking Brake and an electrically assisted brake boost system. A SERVICE BRAKE ASSIST message means a fault in the boost assist system; the manual notes you may hear the boost assist motor running and feel pulsation in the pedal. Those are electrical and control faults, not fluid problems, so a flush will not clear them - they need a scan tool diagnosis.

Doing the flush: what to know before you start

A fluid flush on this car is more than cracking bleeders. Because the LaCrosse has ABS, stability control and brake assist that use the hydraulic brake control module, there is fluid inside that module that a simple gravity bleed may not fully exchange. Many shops use a pressure bleeder and, where the service information calls for it, a scan tool to cycle the ABS valves so the old fluid in the module is purged.

• Use a new, sealed bottle of DOT 3 fluid. Do not reuse fluid you bleed out.
• Follow the bleed sequence and any scan-tool procedure in the factory service information for your VIN.
• Never let the reservoir run dry during the bleed, or you risk pulling air into the ABS module.
• Rear pad work on a car with an Electric Parking Brake typically requires putting the EPB into its service mode with a scan tool before the rear caliper pistons can be retracted. Plan for that if you combine the flush with a rear brake job.
• Finish by confirming a firm pedal with the engine running, then road test at low speed.

If you are doing pads at the same time, a flush is a smart pairing: the calipers are already open, and fresh fluid means the new pads get full performance. For this LaCrosse, we carry 2017-2019 Buick LaCrosse front ceramic brake pads, and you can browse more brake pads, brake rotors and brake hardware kits. If an inspection turns up a weeping caliper or a cracked hose, see our brake calipers and brake hoses.

Frequently Asked Questions

Can I use DOT 4 in my 2017-2019 Buick LaCrosse?

GM specifies DOT 3 for this car, and both the manual and the reservoir cap say so. Using the fluid GM lists is the safe choice. Whatever you use, never add DOT 5 silicone fluid to this system.

How often should the brake fluid be changed on a LaCrosse?

GM's maintenance schedule says to replace brake fluid every five years. If a moisture or boiling point test fails sooner, or the fluid looks dark and contaminated, change it early.

My brake fluid is a little low. Should I add some?

Not without finding out why. GM says the level drops from pad wear or a leak. Check the pads first; if they are fine, look for a leak at the calipers, hoses, lines and master cylinder.

What happens if I never change the brake fluid?

The fluid keeps absorbing water, its boiling point falls, and heavy braking can cause a soft pedal and longer stops. Moisture in the fluid also promotes internal corrosion in calipers, lines and the ABS module.

Where is the brake fluid reservoir on a LaCrosse?

It sits on the master cylinder in the engine compartment. The engine compartment overview in the owner's manual shows its exact location, and the cap is marked with the required fluid type.

Sources

1. Buick LaCrosse Owner's Manual (GM) - DOT 3 specification, GM part number, five-year replacement, do-not-top-off guidance, warning lights, EPB and brake assist messages
2. 49 CFR 571.116, FMVSS 116 Motor Vehicle Brake Fluids (Cornell LII) - DOT 3, DOT 4 and DOT 5 dry and wet boiling points, DOT 5 purple dye, container warning
3. ADVICS Aftermarket - Brake Fluid Boiling Points - hygroscopic glycol-ether fluid, 3.7 percent water wet boiling point definition, follow the owner's manual interval