1989-1997 Nissan 240SX Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 1989-1997 Nissan 240SX takes DOT 3 brake fluid. Nissan's maintenance information for the 1989-95 cars lists "US FMVSS No. 116 or DOT 3," and the 1995 factory service manual says to use Genuine Nissan Brake Fluid or an equivalent DOT 3. Nissan's printed schedule has no fixed mileage for replacing the fluid. It only calls for inspecting the brake lines, pads and rotors. On a car this old, the practical answer is simple: if you can't prove when the fluid was last changed, flush it now.

What the factory manual actually specifies

The spec is the same across both 240SX generations: the S13 (1989-94) and the S14 (1995-98, which covers the 1995-97 US model years in this guide). Here is what Nissan's own service literature says:

The master cylinder reservoir has MAX and MIN lines, and the manual says the level should sit between them. If the level is extremely low, Nissan says to check the system for leaks. A level that has only dropped a little usually just means the pads have worn and the caliper pistons have moved out.

Why the fluid still needs changing, even without a schedule line

DOT 3 is a glycol-ether fluid, and glycol-ether fluids are hygroscopic. That means they pull moisture out of the air through the reservoir vent and the rubber hoses. ADVICS, an OE brake supplier, explains that the "wet" boiling point is measured after the fluid has absorbed 3.7 percent water by volume. It also says DOT 3 typically reaches that point after about a year of use, and DOT 4 after about two. The federal standard for brake fluid (FMVSS 116) shows how big the drop is:

When wet fluid boils in a hot caliper, it forms vapor bubbles. Vapor compresses where liquid won't, so the pedal goes long and soft right when you need it most. Water also corrodes the inside of steel lines, caliper bores and the ABS actuator. Every 240SX is now between roughly 29 and 37 years old, and many have been drifted, autocrossed or tracked, so heat in the fluid is a real concern. Our advice: change DOT 3 at least every one to two years of street use. On a car that sees track or drift days, bleed it before each event. ADVICS also notes that the owner's manual should be the starting point, and on this car the manual leaves the interval to the condition of the fluid.

Signs your 240SX brake fluid is due

• A dark reservoir. Fresh DOT 3 is clear to pale amber. Fluid the color of tea or coffee is old and full of moisture and debris.
• A soft or long pedal that firms up when you pump it. This points to air or vapor in the system.
• Fade after repeated hard stops. If the pedal sinks after a canyon run or a track session, the fluid is boiling.
• The brake warning lamp stays on with the parking brake released. Nissan's check procedure calls for inspecting the system for leaks in this case, because low fluid can trigger the lamp.
• Wet spots at the calipers or hoses, or crusty fittings. Nissan's line check covers cracks, deterioration and leaks at the tubes and hoses, and it says to press the pedal hard with the engine running while you look.

How to flush and bleed it the factory way

The 1995 manual's brake-fluid change procedure is simple: clean the inside of the reservoir, refill it with new fluid, connect a vinyl tube to each bleeder, and pump old fluid out at each wheel until new fluid comes through. The bleed sequence Nissan gives is:

1. Right rear
2. Left rear
3. Right front
4. Left front

At each bleeder, depress the pedal several times, hold it down, open the valve to let air out, close the valve, then release the pedal slowly. Repeat until clear fluid with no bubbles comes out. The manual's cautions are worth following exactly:

• Keep the reservoir above the MIN line the whole time. If it runs dry, you pull air into the master cylinder and have to start over.
• On cars with ABS, turn the ignition off and disconnect the ABS actuator connectors or the battery ground cable before you bleed.
• Never reuse drained fluid, and never let petroleum products such as mineral oil or kerosene touch the system. Nissan warns that they ruin the rubber seals.
• Rinse any spilled fluid off paint with water right away. DOT 3 lifts paint.
• Use a flare-nut wrench on the brake tubes and torque the lines on reassembly to the value in the factory service manual.

Most owners can do this in an hour with a helper, a clear hose and a catch bottle. If the bleeders are seized or rounded, soak them and use a six-point socket before reaching for pliers. A snapped bleeder turns a flush into a caliper job.

What to check or replace while the fluid is out

A flush gives you a good reason to look over the whole system while the wheels are off.

• Rubber hoses. The flex hoses on a 240SX are decades old on most cars. Cracked or swollen hoses let moisture in and balloon under pressure. New brake hoses or stainless brake lines go in easily during a bleed.
• Rotors. The 1995 manual lists front rotors (CL22VF caliper) at 20.0 mm new with an 18.0 mm minimum, and rears (CL11H caliper) at 9.0 mm new with an 8.0 mm minimum. Mike them while the wheels are off. For 1994-96 cars with ABS and 5-lug hubs, we carry the EBC USR slotted rear rotor pair, and there are more brake rotors in the catalog.
• Rear pads. For 1989-97 240SX SE models, the Hawk HPS street rear pads are a solid daily-driver upgrade. The Hawk HP Plus street and track rear pads suit cars that also see track or drift days, where fresh fluid matters most.
• Master cylinder. If the pedal still sinks slowly under steady pressure after a good bleed and there are no external leaks, the master cylinder seals may be bypassing. Browse master cylinders if yours is the original.

Frequently Asked Questions

What brake fluid does a Nissan 240SX use?

DOT 3 brake fluid meeting US FMVSS No. 116. Nissan's 1989-95 maintenance information and the 1995 factory service manual both specify it.

Can I use DOT 4 in my 240SX?

The factory spec is DOT 3. Many owners who track their cars choose a glycol-based DOT 4 for its higher minimum boiling points, but it absorbs moisture too and still needs regular changes. Do not use DOT 5 silicone fluid. It is a different chemistry from what this system was built for.

How often should I flush the brake fluid on a 240SX?

Nissan's US schedule gives no fixed replacement mileage and only calls for inspecting the brake system every 15,000 miles or 12 months (every 7,500 miles or 6 months under severe use). Because DOT 3 absorbs moisture over time, plan on a flush every one to two years on the street, and before every event if the car is tracked or drifted.

What is the correct bleeding order for a 240SX?

Right rear, left rear, right front, left front, according to the 1995 factory service manual. On ABS cars, switch the ignition off and disconnect the ABS actuator connectors or the battery ground cable first.

Why is my 240SX brake pedal still soft after bleeding?

Usually there is still air in the system, often from the reservoir dropping below MIN during the bleed. Other causes are old hoses that swell under pressure or a worn master cylinder. Re-bleed carefully first, then inspect the hoses and master cylinder.

Sources

1. Nissan 240SX 1989-95 Maintenance Information - brake fluid spec: US FMVSS No. 116 or DOT 3
2. Nissan 240SX 1995 Factory Service Manual, MA section - Genuine Nissan Brake Fluid or equivalent DOT 3, maintenance schedules 1 and 2, rotor thickness specs
3. Nissan 240SX 1995 Factory Service Manual, BR section - fluid level check, brake fluid change and bleeding procedure, bleed order, ABS precautions
4. 49 CFR 571.116 (FMVSS 116), Legal Information Institute - DOT 3 and DOT 4 minimum dry and wet boiling points, moisture storage warning
5. ADVICS - Brake Fluid Boiling Points - hygroscopic glycol-ether fluid, 3.7 percent water wet-boiling definition, typical DOT 3 saturation timeline