2013-2018 BMW X1 Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

Every 2013-2018 BMW X1 takes a DOT 4 low viscosity brake fluid, the same type BMW sells as its own DOT 4 LV fluid. Change it on a time schedule, not a mileage one: BMW's Condition Based Service flags a brake fluid change about every two years. Many cars reach that date long before they reach any mileage number.

This guide covers why the X1 needs low viscosity fluid, how the fluid schedule works on both generations sold here, how to tell when the fluid is overdue, and what to check while the brakes are opened up.

Which BMW X1 Generations This Covers

Two X1 generations fall inside the 2013-2018 range in North America. The 2013-2015 X1 is the first-generation E84. It is rear-wheel-drive based. The 2016-2018 X1 is the second-generation F48. It is front-wheel-drive based. Brake pads and rotors differ between the two, but both use the same fluid type and follow the same time-based fluid service. Both generations have four-wheel disc brakes, ABS and BMW's DSC stability control, and those systems are the reason the fluid choice matters.

What Brake Fluid the X1 Uses and Why It Is Low Viscosity

BMW moved its cars to low viscosity DOT 4 fluid as Dynamic Stability Control (DSC) spread across the lineup in the mid-2000s. Every X1 was built with DSC, so every X1 gets the LV fluid. Stability control has to pump fluid to individual calipers at very high pressure, very fast. In deep cold, ordinary brake fluid thickens enough to slow that response. BimmerWorld's brake fluid guide explains that BMW's low viscosity fluid is held to no more than 750 mm2/s at -40 C. Ordinary DOT 4 only has to stay under 1,800 mm2/s. At extreme cold, that makes LV fluid roughly half as thick as the older normal-viscosity type.

The DOT 3 and DOT 4 rows are the federal minimums in FMVSS 116. The LV row is typical of the low viscosity products brake makers sell. What this means for an X1 owner:

• Buy fluid labeled DOT 4 low viscosity (often DOT 4 LV, ESL or ISO Class 6). Genuine BMW fluid carries the part number 81220142156 in the small bottle.
• Do not top off with DOT 3. It has a lower boiling point and is not the fluid the car was engineered around.
• Never use silicone DOT 5. It does not mix with the glycol-based fluid in the system.
• Use sealed fluid. The federal container warning reads: "KEEP BRAKE FLUID CLEAN AND DRY." Once a bottle has been opened, it starts pulling in moisture from the air.

Flush Interval: How BMW Schedules It

BMW does not print a single mileage number for X1 brake fluid. Condition Based Service (CBS) tracks brake fluid by time, because the fluid ages whether the car is driven or not. BMW dealer maintenance schedules describe the fluid as coming due about every two years under CBS. That timer can run out before any mileage milestone, especially on a low-mileage X1. Textar, a brake friction and fluid maker, gives the same general guidance: change brake fluid every two years.

In practice:

• Follow the CBS reminder in the instrument cluster or iDrive. When the brake fluid item turns due, book the service. After the fluid is changed, the shop resets that CBS item.
• If you bought the car used and have no records, change the fluid now. You have no way of knowing how old the fluid in the car is.
• Change it sooner after hard use. Towing, mountain driving and track days all heat the fluid and speed up its breakdown.

Why Old Fluid Is a Problem

Glycol brake fluid is hygroscopic, which means it absorbs water over time. The difference between the dry and wet boiling points in the table shows what that water does. FMVSS 116 lets DOT 4 fall from a 446 F dry minimum to a 311 F wet minimum, and the wet figure is measured with only a few percent water in the fluid. As the boiling point drops, a long downhill stop or repeated hard braking can boil the fluid in the calipers. That creates vapor bubbles, and the pedal suddenly goes soft. Water also corrodes the system from the inside. On an X1, the most expensive part at risk is the DSC/ABS hydraulic unit, with its small valves and pump.

Signs your X1's fluid is overdue

• The brake fluid item in CBS shows as due or overdue.
• The pedal feels softer or travels farther than it used to, especially after repeated stops.
• The fluid in the reservoir looks dark brown instead of clear amber.
• The fluid level has dropped toward MIN. Pad wear can cause some of that drop, but a sudden drop points to a leak.
• A brake warning light is on. BMW of Sterling notes that the brake light can indicate a fluid leak as well as other brake faults. Have it checked before you drive far.

How the Job Is Done and How Hard It Is

A brake fluid flush on an X1 is a moderate DIY job for someone who has bled brakes before. The procedure is the familiar one: fill the reservoir, then push new fluid through each caliper until clean fluid comes out of every bleeder, keeping the reservoir from running low the whole time. Most shops use a pressure bleeder on the reservoir. The reservoir sits on the master cylinder under the hood, and the X1's system holds a modest amount of fluid. Buy at least a liter so you can push old fluid all the way out.

Two points matter on a DSC car:

• Do not let air into the system. A normal flush that never runs the reservoir dry does not need the hydraulic unit cycled. If air gets into the DSC unit, a proper bleed needs a scan tool that can run the pump. At that point it becomes a shop job.
• Reset CBS afterward. The dash reminder does not clear by itself. Some owners reset it from the cluster, and scan tools can reset it too.

If you are not comfortable working under the car with the wheels off, a flush is a short, low-cost service at any European-car shop. Just confirm the shop uses DOT 4 low viscosity fluid and not a generic DOT 3.

What to Check at the Same Time

With the wheels off for bleeding, it is the right time to look at the rest of the brake system:

• Pads and wear sensors. BMW fits pad wear sensors that trigger a warning when the pads get thin. Measure what is left. If the pads are close to the sensor, replace them now while the fluid is fresh. We carry pads for both generations. For the 2016+ F48, there are the EBC Bluestuff NDX front pad set for the F48 X1 and the EBC Yellowstuff front pads for the 2016-2017 X1 xDrive28i. For the rear, there are the EBC Yellowstuff rear pads for the 2016-2018 X1. For the 2013-2015 E84, there are the EBC Bluestuff NDX rear pads for the 2013-2015 X1. Replace the wear sensor whenever it has made contact with the rotor.
• Rotors. Check thickness against the minimum stamped on the rotor, and look for lips, scoring or heat spots. Browse replacement brake rotors if yours are at their limit.
• Hoses and lines. Look for cracked, swollen or wet flex hoses at each corner. See our brake hoses and brake lines.
• Caliper bleeders and slides. A bleeder that will not open or a caliper that drags is easier to deal with now than later.

Frequently Asked Questions

What brake fluid does a 2013-2018 BMW X1 take?

DOT 4 low viscosity fluid, often labeled DOT 4 LV, ESL or ISO Class 6. BMW's own fluid is sold under part number 81220142156. Normal DOT 4 meets the boiling point rules, but it is thicker in the cold than the stability control system was designed for.

How often should I change the brake fluid on my X1?

Follow the Condition Based Service reminder, which schedules brake fluid by time, about every two years. Do not wait for a mileage number. Brake fluid absorbs moisture whether the car is driven or not.

Can I mix DOT 4 LV with regular DOT 4?

Both are glycol-based and will not damage each other, so a small top-off in an emergency will not hurt. But mixing raises the viscosity above the LV spec. At the next service, flush the system with DOT 4 LV only.

Is the X1 brake fluid service the same on the E84 and the F48?

The fluid type and the time-based schedule are the same on both. The pads, rotors and some hardware differ between the 2013-2015 E84 and the 2016-2018 F48, so match brake parts to your exact model year.

Why does my brake fluid service come due when I barely drive?

CBS counts time for brake fluid because moisture absorption depends on time, not distance. A garage-kept X1 driven a few thousand miles a year still needs fresh fluid on schedule.

Sources

1. BimmerWorld - BMW Brake Fluid Types - BMW's switch to low viscosity fluid with DSC, the 750 mm2/s limit at -40 C, genuine part 81220142156
2. 49 CFR 571.116 (FMVSS 116) - Motor vehicle brake fluids - DOT 3 and DOT 4 dry and wet boiling points, viscosity limits, container warnings
3. Textar - Brake Fluid - DOT 4 LV / Class 6 boiling points, two-year change guidance
4. Rick Hendrick BMW - BMW Recommended Maintenance Schedule - CBS triggers brake fluid on a time schedule of about every two years
5. BMW of Sterling - BMW Brake Guide - BMW pad wear sensors, brake warning light and fluid leaks