2014-2020 Infiniti Q50 Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2014-2020 Infiniti Q50 uses Genuine NISSAN Super Heavy Duty Brake Fluid or an equivalent DOT 3 fluid, according to Infiniti's own owner's manuals. Infiniti's maintenance schedule calls for replacing (not just topping off) that fluid every 20,000 miles or 24 months under normal driving, and every 10,000 miles or 12 months if the car is driven under severe conditions.

That is a shorter interval than many owners expect, and it is the one maintenance item on a Q50 that is easy to skip because nothing looks or sounds wrong until the fluid is badly worn out. Below is what the spec means, why the interval exists, how to tell if yours is overdue, and what to service at the same time.

What Brake Fluid the Q50 Takes

Both the 2014 and 2017 Q50 owner's manuals list the same fluid in the capacities and recommended fluids chart: Genuine NISSAN Super Heavy Duty Brake Fluid or equivalent DOT 3. The Do-it-yourself section repeats it: if the level is below the MIN line or the brake warning light comes on, add that fluid up to the MAX line. The manual also warns to use only new fluid from a sealed container, because old or contaminated fluid can damage the brake system, and to keep brake fluid off painted surfaces because it damages paint.

DOT 3 is a federal performance grade, not a brand. Federal Motor Vehicle Safety Standard No. 116 sets the minimum boiling points each grade must meet. Here is how the grades compare:

A note on DOT 4: a glycol-based DOT 4 fluid clears every DOT 3 boiling-point minimum, and fluid makers such as Motul state their DOT 4 is mixable with DOT 3, DOT 4 and DOT 5.1 non-silicone fluids. Many owners who drive hard or track their Q50 use it for the higher boiling point. If you want to stay strictly with the book, Infiniti's wording is DOT 3 or equivalent, so a DOT 3 fluid is the safe default and the right choice for a normal daily driver.

What you must never put in a Q50 is DOT 5 silicone fluid. It is a completely different chemistry. FMVSS 116 even requires DOT 5 silicone fluid to be dyed purple so it can be told apart from DOT 3, DOT 4 and DOT 5.1, which are colorless to amber. Motul's own datasheet says glycol fluids should not be mixed with silicone or mineral oil fluids. DOT 5.1 is glycol-based and is not the same thing as DOT 5, despite the similar name.

The Flush Interval: 20,000 Miles or 24 Months, Halved for Severe Use

Infiniti's online maintenance guide for the Q50 lists brake fluid replacement every 20,000 miles or 24 months for standard driving, and every 10,000 miles or 12 months for severe driving. The 2017 owner's manual schedule matches: brake fluid is marked for replacement, and the severe-service table lists brake fluid at every 10,000 miles or 12 months.

The manual defines severe driving conditions. If most of your driving looks like any of these, use the shorter interval:

• Repeated short trips of less than 5 miles
• Repeated short trips of less than 10 miles with outside temperatures below freezing
• Hot weather in stop-and-go rush hour traffic
• Extensive idling or long distances at low speed, such as police, taxi or delivery use
• Dusty conditions
• Rough, muddy or salt-spread roads
• Using a car-top carrier

Plenty of commuters in the snow belt or in big-city traffic fall into that list without thinking of themselves as severe users. Whichever comes first, miles or months, is the one that counts. A low-mileage Q50 that sits in a garage still needs fresh fluid on the time interval, because the fluid ages whether or not the car moves.

Why Brake Fluid Wears Out

Glycol-based brake fluid is hygroscopic: it absorbs moisture from the air over time. Water lowers the boiling point. That is exactly why FMVSS 116 publishes two numbers for every grade. The dry figure is fresh fluid out of a sealed container. The wet figure is the fluid after it has picked up moisture, and it is much lower. Motul's datasheet notes that the wet boiling point is representative of the fluid after about a year of use.

When hard braking heats worn fluid past its boiling point, vapor bubbles form in the calipers. Unlike liquid, vapor compresses, so the pedal sinks and stopping power drops right when you need it most, such as on a long downhill grade or during repeated stops from highway speed. Moisture in the system also works against the metal parts inside the calipers, lines and ABS hydraulic unit, which is the more expensive long-term problem.

Signs Your Q50 Brake Fluid Is Overdue

• Soft or spongy pedal. The pedal travels farther than it used to or feels mushy, especially after several hard stops.
• Dark or cloudy fluid. Fresh DOT 3 is colorless to amber. Fluid that looks like strong tea or coffee is past due.
• Brake warning light. On the Q50 the same red light covers the parking brake and a low brake fluid level. If it comes on with the parking brake released, Infiniti says to stop and check the fluid level.
• Level dropping between checks. If you have to add fluid often, the manual says to have the system checked, because that points to a leak or worn pads.
• No service record. If you bought the car used and cannot find a brake fluid replacement in the records, assume it is due.

Important: Infiniti's manual says that if the fluid is below the MIN mark, do not drive until the brake system has been checked. A low level is a symptom, not just a maintenance reminder.

How the Job Is Done and What to Replace at the Same Time

A brake fluid flush pushes new fluid through the master cylinder, lines, ABS unit and each caliper until clean fluid comes out of every bleeder screw. The correct bleeding sequence depends on the vehicle, so follow the factory service manual for the Q50 rather than a generic order. Use fluid from a new, sealed bottle every time, and keep the reservoir from running dry during the job or you will pull air into the system, which makes the bleed much harder.

For a home mechanic with a helper or a pressure bleeder, it is a moderate job. The Q50 uses a foot-operated parking brake pedal, so there is no electronic parking brake service mode to deal with. Torque the bleeder screws and wheel lug nuts to the values in the factory service manual.

The smart time to flush is during a pad and rotor job, since you are already at each wheel and pushing the caliper pistons back. Consider these while the car is apart:

• Pads and rotors. Infiniti's severe schedule calls for inspecting pads and rotors every 5,000 miles or 6 months. We carry 2014-2020 Infiniti Q50 front ceramic brake pads from Power Stop, plus a full range of replacement brake rotors and brake pads.
• Brake hoses. The schedule includes inspecting brake lines and cables. Cracked, swollen or soft rubber hoses should be replaced before a flush. See our brake hoses and brake lines.
• Hardware. Fresh clips and slide pin boots keep new pads from dragging. Browse brake hardware kits.

Frequently Asked Questions

What type of brake fluid does a 2014-2020 Infiniti Q50 use?

Infiniti specifies Genuine NISSAN Super Heavy Duty Brake Fluid or an equivalent DOT 3 fluid. It is listed in the capacities and recommended fluids chart of the owner's manual.

Can I use DOT 4 in my Q50?

A glycol-based DOT 4 exceeds every DOT 3 boiling-point minimum in FMVSS 116 and is mixable with DOT 3, so many owners use it, especially for spirited driving. For a standard daily driver, sticking with DOT 3 matches the manual exactly. Never use DOT 5 silicone fluid.

How often should I change the brake fluid on a Q50?

Every 20,000 miles or 24 months under normal driving, and every 10,000 miles or 12 months under severe driving conditions such as short trips, stop-and-go heat, salted roads or dusty conditions, whichever comes first.

Is topping off the same as flushing?

No. Topping off only replaces the fluid that is missing. The moisture-laden fluid in the calipers and lines stays in place. Infiniti's schedule calls for replacement, which means flushing old fluid out of the whole system.

Why is my Q50 brake warning light on?

On the Q50 that light covers both the parking brake and low brake fluid level. Make sure the parking brake is fully released. If the light stays on, check the reservoir level. If it is below MIN, do not drive until the brake system has been checked.

Sources

1. INFINITI USA - 2018 Q50 Brake Fluid Maintenance Guide - 20,000 mi/24 mo standard and 10,000 mi/12 mo severe replacement intervals
2. INFINITI USA - 2023 Q50 Brake Fluid Maintenance Guide - same intervals confirmed for later model years
3. 2014 Infiniti Q50 Owner's Manual - DOT 3 fluid spec, brake warning light behavior, sealed-container and paint warnings
4. 2017 Infiniti Q50 Owner's Manual and Maintenance Information - severe driving definition, severe schedule, foot-operated parking brake
5. 49 CFR 571.116 (FMVSS No. 116), Cornell LII - DOT 3/4/5 dry and wet boiling point minimums and fluid color rules
6. Motul DOT 4 Brake Fluid technical datasheet - moisture absorption, wet boiling point after about a year, mixing compatibility
7. Motul - How to Change Brake Fluid - hygroscopic behavior and signs of worn fluid