2013-2016 Scion FR-S Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2013-2016 Scion FR-S takes fresh DOT 3 or DOT 4 brake fluid that meets FMVSS No. 116, according to the specifications section of the owner's manual. Scion's maintenance schedule calls for replacing it every 30,000 miles or 30 months, whichever comes first, and every 15,000 miles or 15 months if you drive in high humidity or mountainous areas. On manual-transmission cars the same fluid also works the clutch.

What the Factory Specifies for the FR-S

The FR-S owner's manual lists the brake fluid type as "FMVSS No.116 fresh DOT 3 or DOT 4 brake fluid." The clutch on manual-transmission cars gets the same fluid. That second point is easy to miss. If you bleed the brakes on a six-speed car and skip the clutch slave, you leave old fluid in part of the hydraulic system.

Here are the relevant numbers from the manual and the 2015 Scion FR-S Warranty and Maintenance Guide:

"Fresh" matters. Brake fluid absorbs water, and fluid from a bottle that has been open on a shelf for months has already started absorbing it. Use a sealed bottle for each flush.

DOT 3 vs DOT 4: Which One to Use

Both grades are approved, so either is correct. The difference is boiling point. The federal brake fluid standard, FMVSS No. 116, sets these minimums:

The "wet" boiling point is measured after the fluid has absorbed a set amount of water. It is closer to the condition of fluid that has been in a car for a couple of years. DOT 4 keeps more margin at both ends. Many FR-S owners drive canyon roads, run autocross or do track days in this light rear-drive car, so DOT 4 is the sensible pick for most of them. Stick with one grade, and don't top off with fluid of unknown type.

Do not use DOT 5. DOT 5 is silicone-based, and the standard requires it to be dyed purple so it can be told apart. DOT 3 and DOT 4 are glycol-based and must be colorless to amber. The FR-S is not specified for silicone fluid, and silicone does not mix with the glycol fluid already in the system.

Why Brake Fluid Needs Replacing

Glycol brake fluid absorbs moisture from the air. As the water content rises, the boiling point falls toward the wet figure in the table above. Hard braking makes the calipers hot. If the fluid near them boils, it forms vapor bubbles. Vapor compresses, so the pedal goes soft or sinks toward the floor. That is fade from boiling fluid, and it shows up at the worst possible time: on the third hard stop coming down a hill, or at the end of a long straight.

Water in the fluid also promotes internal corrosion in the calipers, the master cylinder and the ABS hydraulic unit. According to Scion's Quick Reference Guide, the FR-S uses ABS, Electronic Brake-force Distribution, Brake Assist, Vehicle Stability Control and Traction Control. All of them work through that hydraulic unit, and its valves have tight clearances that do not tolerate corrosion or debris.

That is why the federal standard requires every bottle to carry a warning to keep brake fluid clean and dry and to keep the container tightly closed. It is also why Scion shortens the interval to 15,000 miles or 15 months in humid climates or mountain driving. In those conditions the fluid both picks up water faster and gets heated harder.

Signs Your FR-S Is Due for a Flush

• Time or mileage. The fluid is due if it has been 30 months or 30,000 miles, or if you cannot find a record of the last flush. Many 2013-2016 cars are well past it.
• Dark fluid. New DOT 3 and DOT 4 are colorless to amber. Fluid that has turned dark brown in the reservoir has aged.
• Soft or long pedal after hard use. If the pedal feels fine around town but goes soft after a few hard stops, the fluid is probably boiling.
• Brake warning light. The brake system warning light can come on when the fluid level is low. Low fluid usually means worn pads or a leak, so find the cause before you top it off.
• Before a track day. Fresh DOT 4 before an event is cheap insurance. Many owners who track the car flush far more often than the factory schedule.

It is normal for the level to drop slowly as the pads wear, because the caliper pistons move out and fluid fills in behind them. If the level is low and the pads are still thick, look for a leak at the calipers, lines and hoses. On manual cars, check the clutch slave cylinder too.

How to Flush the FR-S Brake Fluid

A full flush replaces all the fluid in the system, not just the fluid in the reservoir. The basic process:

1. Remove as much old fluid from the reservoir as you can and refill it with fresh DOT 3 or DOT 4 from a sealed bottle.
2. Bleed each caliper, usually starting with the wheel farthest from the master cylinder and working toward the closest. Follow the order in the factory service manual for your car.
3. Push fluid through each bleeder until it runs clean and free of bubbles.
4. Don't let the reservoir run low during the job. If air gets drawn into the ABS unit, purging it can require a scan-tool procedure.
5. On manual-transmission cars, bleed the clutch slave cylinder too.
6. Tighten the bleeder screws to the torque in the factory service manual. Fill the reservoir to the MAX line and make sure the pedal is firm before you drive.

With a helper or a pressure bleeder, this is a manageable home-garage job for a careful DIYer. Wipe up any spills right away, since glycol brake fluid damages paint.

What to Do at the Same Time

The factory schedule calls for inspecting the brake pads, discs, lines and hoses every 15,000 miles or 15 months. A fluid flush with the wheels off is the ideal time to do it:

• Check pad thickness against the 0.06 in. (1.5 mm) wear limit.
• Look at the rotors for scoring, a lip at the edge, or cracks.
• Check the rubber hoses for cracks and swelling.

If the pads are close to the limit, replace them first and then flush, so you only bleed the system once. For owners who drive the FR-S hard, we carry Hawk Performance ER-1 rear brake pads for the 2013-2016 Scion FR-S and a Hawk Talon drilled and slotted front rotor set for the 2013 FR-S. You can also browse all brake pads, brake rotors and brake hoses.

Frequently Asked Questions

What brake fluid does a Scion FR-S use?

The owner's manual specifies fresh DOT 3 or DOT 4 brake fluid that meets FMVSS No. 116. DOT 4 has a higher boiling point and is the better choice for spirited or track driving.

How often should I change the brake fluid on my FR-S?

Scion's maintenance guide says every 30,000 miles or 30 months, whichever comes first. In high humidity or mountainous areas, it drops to every 15,000 miles or 15 months. If you track the car, flush it more often than that.

Can I mix DOT 3 and DOT 4 in my FR-S?

Both are glycol-based and both are approved for the car. Topping off with the other grade will not cause damage, but the mix will only perform as well as the lower grade. The cleanest approach is to flush the whole system with one fluid.

Does the FR-S clutch use brake fluid?

Yes. On manual-transmission cars, the owner's manual specifies the same FMVSS No. 116 DOT 3 or DOT 4 brake fluid for the clutch. Bleed the clutch slave cylinder when you flush the brakes.

Can I use DOT 5 silicone brake fluid?

No. The FR-S is specified for DOT 3 or DOT 4 only. DOT 5 is silicone-based and does not mix with the glycol fluid in the system.

What happens if I never change the brake fluid?

The fluid keeps absorbing water, so its boiling point keeps dropping. The pedal gets more likely to go soft under hard braking, and corrosion builds up inside the calipers, master cylinder and ABS unit. Those parts cost far more to replace than a flush.

Sources

1. 2014 Scion FR-S Owner's Manual, Specifications (p. 387) - Brake and clutch fluid type, pedal free play, pad wear limit, parking brake travel
2. 2015 Scion FR-S Warranty and Maintenance Guide (Toyota) - Brake fluid replacement interval, severe-service interval, brake line and pad inspection intervals
3. 49 CFR 571.116, FMVSS No. 116 Motor Vehicle Brake Fluids - DOT 3 and DOT 4 boiling point minimums, fluid colors, moisture warning label
4. 2014 Scion FR-S Quick Reference Guide - ABS, EBD, Brake Assist, VSC and TRAC systems, brake system warning light