2003-2014 Acura TSX Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

Every 2003-2014 Acura TSX takes a glycol-based DOT 3 brake fluid. The owner's manuals call for Honda or Acura Heavy Duty Brake Fluid DOT 3 and tell you to replace it every 3 years, regardless of what the maintenance messages say. DOT 3 or DOT 4 from a sealed container is acceptable as a temporary substitute, and DOT 5 silicone fluid must never go in the system.

What Acura Specifies for the TSX

We checked two factory owner's manuals that bracket the TSX's two generations: the 2006 TSX (first generation) and the 2010 TSX (second generation). Both say the same thing about brake fluid, with only the branding changed. The 2006 book names Honda Heavy Duty Brake Fluid DOT 3; the 2010 book names Acura Heavy Duty Brake Fluid DOT 3. Same class of fluid, same rules around it.

The manual is blunt about substitutes: it warns that non-factory brake fluid can cause corrosion and shorten the life of the system, which is why it asks for a flush back to the Heavy Duty DOT 3 once a temporary fluid has been used. If you own a 2003-2005 or a 2011-2014 car, the owner's manual in your glovebox is the final word, but we found no change in fluid type between the two generations we checked. When in doubt, read the reservoir cap, which carries the fluid rating.

Why the Interval Is Time-Based, Not Mileage-Based

Glycol-based DOT 3 and DOT 4 fluids are hygroscopic: they pull moisture out of the air through the reservoir vent, the rubber hoses and the seals. A TSX that sits in a garage absorbs water on the calendar just like one that commutes every day, which is why Acura puts the fluid on a 3-year clock instead of leaving it to mileage-based reminders alone.

Water in the fluid does two things. It lowers the boiling point, and it gives corrosion a foothold inside the caliper bores, the ABS modulator and the steel lines. Federal Motor Vehicle Safety Standard 116 sets minimum boiling points that show how much moisture costs you:

The "wet" figure is measured after the fluid has absorbed water - ADVICS, an OE brake supplier, describes that test point as 3.7 percent water by volume. That is the gap between fresh and worn-out DOT 3: the minimum drops from 401 F to 284 F. When fluid in a caliper boils during a long downhill or repeated hard stops, the vapor compresses where liquid would not, and the pedal goes soft or sinks toward the floor.

Why You Cannot Just Use DOT 5

DOT 5 has the highest boiling point in the table, so owners sometimes assume it is an upgrade. It is not, for this car. FMVSS 116 requires DOT 5 to be labeled as silicone base and dyed purple; DOT 3, DOT 4 and DOT 5.1 are glycol-based and colorless to amber. Silicone fluid does not mix with the glycol fluid already wetting the lines, seals and ABS unit, and the TSX manual states plainly that DOT 5 can cause extensive damage. Stick with DOT 3, or a sealed DOT 4 as a short-term stand-in.

Signs Your TSX Is Overdue for a Flush

• Dark fluid. Fresh glycol fluid is clear to light amber. Brown or tea-colored fluid in the reservoir has been in service a long time.
• No record of a flush. If the car is past 3 years and nothing in the service history says brake fluid was replaced, assume it is due. The 2006 manual's maintenance record even tells you to write brake fluid replacement in by hand below the coded items.
• Soft or fading pedal after hard use. A pedal that is firm when cold but gets longer after a mountain descent points at moisture-laden fluid.
• BRAKE FLUID LOW message. The multi-information display shows this when the level is at or below MIN. Low fluid usually means worn pads (the caliper pistons sit farther out) or a leak. Do not just top it off - have the pads and lines inspected, as the manual advises.

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

A flush replaces all the fluid in the system, not just what is in the reservoir. Old fluid is pushed out at each caliper bleeder screw until clean fluid appears, while the reservoir is kept above MIN so no air gets drawn into the master cylinder or ABS modulator. Follow the bleed sequence and any ABS procedure in the factory service manual for your year. Use only fluid from a freshly opened, sealed container - an opened bottle on the shelf has already been absorbing moisture. Brake fluid also damages paint, so wipe up spills right away.

For a DIYer with a helper or a one-person bleeder, a flush is a moderate job. The two common mistakes are letting the reservoir run dry mid-bleed and rounding off seized bleeder screws on an older car.

Because the system is open anyway, a flush is the cheapest time to handle related work:

• Pads and rotors. If the fluid level has dropped toward MIN, measure the pads. For 2009-2014 TSX 2.4 models we carry EBC Redstuff ceramic rear brake pads for quiet, low-dust daily driving, EBC Greenstuff 2000 rear pads, and EBC Yellowstuff street and track rear pads for spirited driving. Matching EBC GD Sport slotted rear rotors are available too. Browse more in our brake pads and brake rotors collections.
• Brake hoses. Cracked or swollen rubber hoses admit moisture and flex under pressure. On 2003-2006 TSX models, the Russell stainless steel braided brake line kit replaces them and firms up pedal feel. See all options in brake lines.
• Clutch fluid on manual cars. Manual-transmission TSXs have a separate clutch reservoir that uses the same brake fluid, so it makes sense to refresh that circuit at the same visit.

Frequently Asked Questions

What brake fluid does an Acura TSX use?

DOT 3. The owner's manuals specify Honda or Acura Heavy Duty Brake Fluid DOT 3. A DOT 3 or DOT 4 fluid from a sealed container can be used temporarily, followed by a flush back to the factory fluid.

How often should I flush the brake fluid on my TSX?

Every 3 years, according to the owner's manual, regardless of the maintenance messages on the multi-information display. Replace it sooner if a maintenance message calls for it.

Can I use DOT 4 in my TSX?

As a temporary replacement from a sealed container, yes - the manual allows it. It then recommends flushing and refilling with the Heavy Duty DOT 3 as soon as possible.

Is DOT 5 brake fluid safe for a TSX?

No. DOT 5 is silicone based, and the TSX manual states it is not compatible with the braking system and can cause extensive damage. DOT 5.1 is a different, glycol-based fluid; do not confuse the two.

Does the manual-transmission TSX need a different clutch fluid?

No. The clutch reservoir uses the same fluid specified for the brake system, and its level should also sit between MIN and MAX.

Why is my BRAKE FLUID LOW message on?

The level is at or below the MIN mark. The most common causes are worn brake pads or a leak. Have the brakes inspected rather than simply adding fluid.

Sources

1. 2010 Acura TSX Owner's Manual, Brake and Clutch Fluid - Acura Heavy Duty DOT 3, 3-year replacement, DOT 5 warning, MIN/MAX level
2. 2006 Acura TSX Owner's Manual (Honda techinfo) - Honda Heavy Duty DOT 3, temporary DOT 3/DOT 4 substitute, corrosion warning, 3-year interval, clutch fluid, BRAKE FLUID LOW message
3. 49 CFR 571.116, FMVSS 116 Motor Vehicle Brake Fluids - dry and wet boiling point minimums, DOT 5 silicone labeling and purple color
4. ADVICS: Brake Fluid Boiling Points - hygroscopic glycol fluid, 3.7 percent water wet test point, vapor and spongy pedal