2006-2007 Lexus GS300 Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2006-2007 Lexus GS300 uses DOT 3 glycol-based brake fluid. Lexus supplied Toyota Genuine DOT 3 Brake Fluid for its own recall repairs on this car, and Lexus dealer maintenance schedules call for replacing the brake fluid at the 30,000-mile / 36-month service and again at 60,000 miles / 72 months. If you own a 2006 GS300, there is also a brake master cylinder seal recall tied directly to what fluid gets put in the car, so the fluid choice matters more here than on most sedans.

What brake fluid the GS300 takes

The third-generation GS300 runs a conventional hydraulic brake system: a master cylinder bolted to a vacuum brake booster, four-wheel disc brakes and ABS with stability control. It is not the electronically controlled brake system used on the hybrid GS450h, so a standard flush and bleed applies.

The fluid is DOT 3. When Lexus wrote the repair instructions for Safety Recall ALG, which covers certain 2006 GS 300 cars, the only fluid listed for the job was Toyota Genuine DOT 3 Brake Fluid, part number 00475-1BF03. Check the cap of the master cylinder reservoir and your owner's manual as well; the fluid grade is marked there.

DOT 3 is a federal standard, FMVSS No. 116. That standard sets the minimum boiling points each grade must meet, which is the whole reason brake fluid has to be changed on a schedule:

The "wet" number is the fluid after it has absorbed moisture. Glycol fluid pulls water out of the air through the reservoir vent and the rubber hoses, and every bit of water drags the boiling point down toward that wet figure. Federal rules even require the bottle to tell you to keep the container clean and tightly closed to prevent absorption of moisture. Never put silicone DOT 5 in a GS300; it is a different chemistry and does not belong in a system built for glycol fluid.

The 2006 GS300 recall: why fluid choice matters on this car

In October 2010 Lexus filed a defect report with NHTSA (recall 10V499, Lexus campaign ALG) covering roughly 28,700 2006 GS 300s along with 2006 IS 250 and IS 350 and 2004-2006 RX 330 models. The affected Lexus cars were built from early February 2003 to mid-February 2006, so not every 2006 GS300 is included and 2007 models are not listed.

Here is the mechanism, in Lexus's own terms. The brake fluid used at the factory contains polymers that act as lubricants for brake parts. If the car later gets a replacement fluid with no polymers, or only small amounts, the rubber cup seal at the rear of the master cylinder can dry out and curl as the piston moves. A small amount of fluid then leaks past that seal into the brake booster. You see:

• The red brake warning lamp comes on (the reservoir level has dropped)
• If you keep driving and topping up without fixing it, a softer, spongier pedal
• Braking performance that gradually gets worse

The dealer remedy replaces the master cylinder cup with a redesigned one at no charge, and if leaked fluid has damaged the brake booster, the booster is replaced too. Lexus quoted the job at about two hours. If you own a 2006 GS300, run your VIN on the NHTSA recall lookup or ask a Lexus dealer to confirm the campaign has been completed before you do anything else to the brakes.

The practical takeaway for every GS300 owner, recalled or not: use a quality DOT 3 fluid that meets the factory spec, from a sealed bottle, and do not mix in whatever is left on the garage shelf.

Flush interval: 30,000 miles or 36 months

Lexus dealer service schedules list "Replace Brake Fluid" at the 36-month / 30,000-mile service and again at the 72-month / 60,000-mile service. Treat that as time or mileage, whichever comes first. A GS300 that sits in a garage and only covers a few thousand miles a year still absorbs moisture through the vent and hoses, so the calendar interval is the one most low-mileage owners should watch.

Your owner's manual and the Lexus maintenance guide for your model year are the final word, and hard use such as mountain driving, stop-and-go heat or track days is a reason to change it sooner. Many shops also recommend a flush whenever pads and rotors are replaced, since the system is already open and you are pushing old fluid back up the lines.

Signs your GS300 brake fluid is due

• Color: new DOT 3 is colorless to amber. Dark brown, grey or black fluid in the reservoir is old or contaminated.
• Level drop: pads wear and the level falls slowly over years, but a noticeable drop between services points to a leak. On a 2006 car, a falling level plus the brake warning lamp is exactly the recall symptom.
• Pedal feel: a soft or long pedal, especially after hard stops or a long downhill, is what moisture-lowered boiling point feels like.
• Mileage and age: if there is no record of a flush in the last three years, assume it is due.

How the flush is done and how hard the job is

A brake fluid flush on the GS300 is a moderate job for a home mechanic with a helper or a pressure bleeder:

1. Remove as much old fluid from the master cylinder reservoir as you can and refill with fresh DOT 3.
2. Bleed each caliper in the order given in the factory repair manual, pushing fluid through until it comes out clean and bubble-free.
3. Never let the reservoir run empty during the job; that lets air into the master cylinder and turns a flush into a much longer bleed.
4. Do not reuse the fluid that comes out, and wash any spill off paint right away with water. Brake fluid damages painted surfaces.
5. Wear eye protection. Lexus's own recall instructions warn that bleeding can spray fluid.
6. Top the reservoir to the MAX line, check for a firm pedal with the engine running, and road test before normal driving.

Torque the bleeder screws to the value in the factory service manual; they are small and strip easily. If the pedal will not firm up after a thorough bleed, or the ABS warning comes on, have a shop with a scan tool finish the job, since air trapped in the ABS unit may need an actuator-assisted bleed.

What to replace at the same time

Because the fluid interval lines up with typical pad life, it is common to do both on the same weekend. Inspect the pads and rotors while the wheels are off. We carry EBC Yellowstuff rear brake pads for the 2006-2007 GS300 3.0L, and you can browse our full range of brake pads and brake rotors. Old rubber flex hoses that are cracked or swollen are worth replacing while the system is being bled anyway; see our brake hoses. If a leak has already damaged the master cylinder or booster on a car outside the recall, our master cylinders and brake boosters collections are the place to start.

Frequently Asked Questions

Can I use DOT 4 in my Lexus GS300?

The factory fluid, and the fluid Lexus used for its own recall repairs, is DOT 3. DOT 4 is also glycol-based and has higher minimum boiling points, but on a 2006 GS300 the recall history makes a fluid that meets the Lexus spec the safest choice. Whatever you use, fill from a fresh, sealed bottle and never use silicone DOT 5.

How often should I change the brake fluid on a 2007 GS300?

Lexus dealer schedules list brake fluid replacement at 30,000 miles or 36 months, then again at 60,000 miles or 72 months, whichever comes first. Check your model-year maintenance guide to confirm.

Is my 2006 GS300 part of the brake master cylinder recall?

Maybe. Recall 10V499 (Lexus campaign ALG) covers certain 2006 GS 300s built through mid-February 2006, not every car. Enter your VIN on the NHTSA recall site or ask a Lexus dealer, who can check it in their system.

Why is my brake warning light on but the brakes feel fine?

On this car the red brake warning lamp usually means the fluid level in the reservoir has dropped. Lexus notes the pedal feel does not change immediately when the lamp first comes on, but you should still have it diagnosed promptly, especially on a 2006 model covered by the seal recall.

Does a brake flush fix a spongy pedal?

It fixes a pedal that is soft because of old, moisture-laden fluid or air in the lines. It does not fix a leaking master cylinder seal, a failing booster or worn pads, so if the pedal is still soft after a proper bleed, look further.

Sources

1. NHTSA / Lexus Safety Recall ALG dealer bulletin and technical instructions - covered 2006 GS 300s, production period, polymer-fluid cause, cup and booster remedy, Toyota Genuine DOT 3 fluid part number, bleeding precautions
2. NHTSA / Toyota recall announcement, October 20, 2010 - recall scope, warning lamp and spongy pedal symptoms
3. 49 CFR 571.116, FMVSS No. 116 Motor Vehicle Brake Fluids - DOT 3, DOT 4 and DOT 5 dry and wet boiling points, container moisture warning, fluid color
4. Crown Lexus service maintenance schedule - brake fluid replacement at 36 months / 30K and 72 months / 60K
5. Lexus of Northborough: Is it time to replace your brake fluid - fluid color and level warning signs, flushing with pad and rotor jobs