1999-2009 Honda S2000 Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

The Honda S2000 is specified for DOT 3 brake fluid. Honda's own owner's manuals call for Genuine Honda DOT 3 (later worded Honda Heavy Duty Brake Fluid DOT 3), allow DOT 3 or DOT 4 from a sealed container only as a temporary replacement, and prohibit DOT 5. The flush interval is time-based: the 2000 manual schedules a brake fluid replacement at 45,000 miles or 3 years, whichever comes first, and the 2006 manual says to replace it every 3 years regardless of the maintenance minder.

What Honda Specifies for the S2000

Both the early and late S2000 owner's manuals say the same thing about fluid type, with slightly different wording. The 2000 manual reads "Always use Genuine Honda DOT 3 brake fluid." The 2006 and 2007 manuals change the name to Honda Heavy Duty Brake Fluid DOT 3. In every version, if the Honda fluid is not available you may use only DOT 3 or DOT 4 fluid from a sealed container as a temporary replacement, and Honda then recommends having the system flushed and refilled with its DOT 3 fluid as soon as possible, warning that non-Honda fluid can cause corrosion and shorten the life of the system.

The one hard no is DOT 5. Honda states that brake fluid marked DOT 5 is not compatible with the S2000's braking system and can cause extensive damage. DOT 5 is silicone-based and does not mix with the glycol-based DOT 3 and DOT 4 fluids the car was built around.

The Flush Interval, and Why It Is Time-Based

On the 2000 model year schedule, "Replace brake fluid" appears at 45,000 miles / 3 years and again at 90,000 miles / 6 years. Honda tells owners to service at the distance or the time, whichever comes first, and the Severe Conditions schedule lists the brake fluid at those same points. The 2006 manual moved the car to an on-dash maintenance display but kept brake fluid outside it: independent of the maintenance minder messages, replace the brake fluid every 3 years. Honda also tells you to write the brake fluid replacement in the maintenance record, because the display will not remind you.

The reason the interval is in years rather than miles is moisture. DOT 3 and DOT 4 are glycol-based and absorb water from the air over time, even in a car that sits all winter. Federal Motor Vehicle Safety Standard 116 shows how much that matters by setting two boiling-point minimums for each grade: a dry figure for fresh fluid and a wet figure for fluid that has taken on moisture.

The DOT 5 row is there for comparison only; the S2000 must not use it. The gap between the dry and wet columns is the point: as fluid ages and picks up water, its boiling point drops toward the wet figure. On a car that gets driven hard on back roads, autocrossed or tracked, low-boiling fluid is what turns into a soft or sinking pedal after repeated hard stops. Owners who drive that way often flush more often than the 3-year schedule. Honda's schedule is the floor, not the ceiling.

Signs the Fluid Needs Attention

• The calendar. If you cannot find a record of a flush in the last 3 years, it is due. Many S2000s are stored for part of the year, and sitting does not stop moisture uptake.
• Low reservoir level. Honda says to check the reservoirs monthly. If the brake level is at or below the MIN mark, the manual says the brake system needs attention and should be inspected for leaks or worn pads. Pads wearing down draw fluid into the calipers, so a slowly falling level with no visible leak usually points to pad wear.
• Brake system indicator on while driving. Honda says this usually means the fluid level is low. Press the pedal lightly: if it feels normal, check the level at the next stop and have the system inspected. If the pedal does not feel normal, take immediate action.
• Soft or long pedal after hard use. A pedal that goes long after a spirited run and comes back once the brakes cool is classic boiled, wet fluid.
• Dark fluid. Fresh DOT 3 is light and clear. Darkened fluid is old, though color alone does not tell you the moisture content; the service date does.

Do Not Forget the Clutch Reservoir

The S2000 has two fluid reservoirs under the hood: one for the brakes and a separate one for the hydraulic clutch. Honda's instruction for the clutch system is to use the same fluid specified for the brake system, and it notes that a low clutch level can indicate a leak in the clutch system. The clutch hydraulics see the same moisture uptake, and old clutch fluid is a common reason a clutch pedal starts to feel inconsistent. When you flush the brakes, flush the clutch circuit with the same DOT 3 at the same time so both systems start fresh on the same date.

How the Flush Is Done, and What to Replace With It

A flush means pushing fresh fluid through every bleeder until clean fluid comes out, not just topping off the reservoir. The S2000 has four-wheel disc brakes with ABS, so the job is a four-corner bleed plus the clutch. Use a fresh, sealed bottle every time; federal rules require brake fluid containers to warn buyers to keep fluid clean and dry and store it only in its original, tightly closed container, because an opened bottle absorbs moisture on the shelf. Follow the bleed sequence and any ABS procedure in the factory service manual, and torque bleeder screws and lug nuts to the values in that manual.

The flush is the natural time to handle anything that requires opening the hydraulic system anyway:

• Brake hoses. On a car this age the factory rubber hoses may be original. A Russell stainless steel braided brake line kit for the 2000-2006 S2000 replaces them and gives a firmer pedal, and since the system gets bled after the swap you only do one flush. See all stainless braided brake lines.
• Rotors. If you are already at the wheels, check rotor thickness and surface. For a slotted street or track upgrade, the DBA 4000 Series T3 slotted front rotor for the 2000-2005 S2000 pairs with the matching DBA 4000 T3 rear rotor. The DBA Street Series T2 slotted front rotor is the street-focused option, and GiroDisc A1-104 slotted front rotors cover every S2000 model year.
• Big brake kit. For a dedicated track car, the Brembo GT-S front big brake kit for the 1999-2005 S2000 replaces the front calipers and rotors, and a full flush is part of that install.

Browse the rest of our brake parts by component.

How Hard Is the Job?

A brake and clutch flush on the S2000 is a manageable driveway job for someone who has bled brakes before. It needs the car safely supported on stands, the correct wrench for the bleeders, clear tubing, a catch bottle, and either a helper for the two-person pedal method or a pressure bleeder. The mistakes to avoid are letting the reservoir run dry during the bleed, which pulls air into the system, reusing fluid from an old opened bottle, and spilling fluid on paint. If the pedal is not firm when you are done, do not drive the car; bleed again or have a shop finish the job.

Frequently Asked Questions

Can I use DOT 4 in my S2000?

Honda allows DOT 3 or DOT 4 from a sealed container only as a temporary replacement when its own DOT 3 fluid is not available, then recommends flushing and refilling with Honda DOT 3 as soon as possible. Many owners who track their cars choose a high-boiling DOT 4 anyway, but that is outside Honda's written specification, so understand the tradeoff before you choose it.

How often should I flush S2000 brake fluid?

Honda's schedule calls for replacement every 3 years (the 2000 manual also lists 45,000 miles, whichever comes first). Cars that see hard driving, autocross or track days benefit from flushing more often than that.

Is DOT 5 safe in an S2000?

No. Honda states DOT 5 is not compatible with the S2000's braking system and can cause extensive damage. DOT 5 is silicone-based and should never be mixed into a DOT 3 system.

Does the maintenance minder tell me when the brake fluid is due?

Not on the S2000. The 2006 manual says to replace the brake fluid every 3 years independent of the maintenance minder messages, so track it by date in your service records.

Does the clutch use the same fluid?

Yes. The clutch has its own reservoir, and Honda says to fill it with the same fluid specified for the brake system. Flush both at the same time.

Should I replace brake lines when I flush the fluid?

If the hoses are original or cracked, doing them during the flush saves a second bleed. A stainless braided line kit also gives a firmer pedal feel than aged rubber hoses.

Sources

1. Honda 2000 S2000 Online Reference Owner's Manual - Genuine Honda DOT 3 spec, DOT 3/DOT 4 temporary substitute, DOT 5 prohibited, 45,000 mi / 3 yr brake fluid replacement on Normal and Severe schedules, clutch uses same fluid
2. Honda 2006 S2000 Online Reference Owner's Manual - Honda Heavy Duty Brake Fluid DOT 3, replace every 3 years independent of maintenance minder, brake system indicator guidance
3. Honda S2000 2007 Owner's Manual, Brake and Clutch Fluid page - same DOT 3 specification and MIN/MAX level check in the late model years
4. 49 CFR 571.116, FMVSS 116 Motor Vehicle Brake Fluids - dry and wet boiling-point minimums for DOT 3, DOT 4 and DOT 5, container labeling and moisture warnings