2007-2012 Hyundai Elantra Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2007-2012 Hyundai Elantra uses glycol-based DOT 3 brake fluid, and Hyundai's owner's manual for the 2011-2012 car approves DOT 3 or DOT 4. DOT 4 is the better pick if you are flushing the system anyway, because it has a higher boiling point and is compatible with DOT 3. Never use DOT 5 silicone fluid or any mineral oil in an Elantra.

How often to flush comes down to time more than miles: brake fluid pulls moisture out of the air every day the car sits, so an older Elantra that has never had its fluid changed is almost certainly overdue, even with low mileage.

What Fluid the Elantra Takes, by Generation

This range covers two Elantra sedan generations plus the Elantra Touring wagon. The fluid family is the same across all of them, but the paperwork words it slightly differently.

The HD service manual lists the brake system as a tandem-type master cylinder feeding a vacuum brake booster, with ventilated front discs of 275 mm (10.83 in) and solid rear discs of 262 mm (10.31 in). The fluid specification line in that same manual reads DOT 3. For the 2011-2012 car, the owner's manual tells you to use only hydraulic brake fluid conforming to DOT 3 or DOT 4.

The reservoir cap on your car is the final word. If it is printed with a spec, match it.

DOT 3 vs DOT 4 vs DOT 5: What the Numbers Mean

DOT ratings come from Federal Motor Vehicle Safety Standard 116, which sets minimum boiling points for each grade. There are two numbers that matter: the dry boiling point (fresh fluid out of a sealed bottle) and the wet boiling point (fluid that has absorbed water).

DOT 5 has the highest numbers on paper, but it is silicone-based and must be labeled "DOT 5 SILICONE BASE." It does not mix with the glycol fluid already in an Elantra, and Hyundai does not list it. Stick with DOT 3 or DOT 4.

You can top off DOT 3 with DOT 4 and the other way around, since both are glycol fluids. Just know that mixing a little DOT 4 into old DOT 3 does not give you DOT 4 performance. You only get the higher boiling point after a complete flush and refill.

Why Old Brake Fluid Goes Bad

Glycol brake fluid is hygroscopic: it absorbs water. The moisture gets in through the reservoir vent, the rubber hoses and every time the cap comes off. You cannot see it happen, and it does not show up as a lower fluid level.

Water in the fluid does two kinds of damage:

• Lower boiling point. Look at the table: DOT 3's minimum drops from 205 C dry to 140 C wet. On a long downhill or in hard stop-and-go driving, heat soaks from the pads into the caliper and the fluid. If the fluid boils, it forms vapor bubbles, and vapor compresses. The pedal goes soft or sinks toward the floor right when you need it.
• Internal corrosion. Water left sitting in steel lines, caliper bores and the ABS hydraulic unit leads to rust and pitting. That is how a skipped flush turns into sticking calipers or a failed master cylinder years later.

Old fluid also darkens as it picks up contamination. Fresh DOT 3 and DOT 4 are required to be colorless to amber, so fluid that looks like cola is telling you something.

How Often to Flush an Elantra's Brake Fluid

Check the maintenance schedule in your owner's manual first and follow it. The owner's manual also tells you to check the level between the MIN and MAX marks periodically.

As a general industry guideline, a common replacement interval for glycol brake fluid is around every two years or 30,000 miles for normal driving, with shorter intervals for hard use. On a car that is now 14 to 19 years old, the practical rule is simple:

• If you have no record of a brake fluid flush, do one now.
• If the fluid is dark, or a moisture test pen reads high, flush it.
• If you are replacing a caliper, hose or master cylinder, flush the whole system while it is open.
• If you tow, drive in the mountains, or carry heavy loads, stay on the short side of the interval.

A moisture test pen is cheap and fast: dip the probes into the reservoir and it reads approximate water content.

How to Flush the Fluid on a 2007-2012 Elantra

A flush is a two-person, one-hour job for most home mechanics. The basic process:

1. Clean the reservoir cap and the area around it before opening. The manual specifically warns against letting dirt in.
2. Use a clean turkey baster or syringe to pull most of the old fluid from the reservoir, then refill with fresh DOT 3 or DOT 4 from a sealed bottle.
3. Bleed each wheel in the order given in the service manual, pushing fluid through until it comes out clean and bubble-free.
4. Never let the reservoir run below MIN during bleeding, or you will pull air into the master cylinder and the ABS unit.
5. Top off to the MAX line and test the pedal before driving. It should be firm and stay high.

Two warnings from the Hyundai manual worth repeating: do not let brake fluid touch the paint, because it will damage it, and do not let even a few drops of mineral-based oil such as engine oil into the system, because it attacks the rubber seals. Use a dedicated funnel and clean containers.

If the pedal is still soft after a careful bleed, air may be trapped in the ABS hydraulic unit, which can need a scan tool to cycle the valves. That is a job for a shop with the right equipment.

What to Check While You Are in There

A flush is a good time to look at the parts that share that fluid:

• Pads. Worn pads push the caliper pistons out further, which drops the reservoir level. A low reservoir with no leak usually means thin pads, not missing fluid. If yours are due, see our brake pads for daily drivers or, for the 2007-2008 sedan, the EBC Redstuff ceramic front pad set for the 2007-2008 Elantra 2.0L.
• Elantra Touring owners can look at the EBC Greenstuff 2000 front pads for the 2009-2012 Elantra Touring or the EBC Redstuff ceramic front pads for the Touring.
• Hoses and lines. Cracked rubber hoses let in moisture and can balloon under pressure. Replacements are in our brake hose collection.
• Calipers. A caliper that drags or leaks at the piston boot is often the long-term result of wet fluid. See replacement brake calipers.
• Leaks. The Hyundai manual says a system that needs frequent fluid additions should be inspected. Brake fluid does not get used up; if you keep adding it, it is leaking somewhere.

Related Recall: ABS Module on 2007-2010 Elantra and 2009-2011 Touring

This is not a fluid problem, but it lives right next to the brake hydraulics. Under NHTSA recall 20V-061 (Hyundai campaign 188), certain 2007-2010 Elantra sedans and 2009-2011 Elantra Touring wagons have an ABS module that stays powered with the car off. If moisture gets into the module's circuit, it can short and create an engine-compartment fire risk, even when parked. Hyundai states the short does not affect brake system operation. The free remedy is a relay installed in the main junction box, and Hyundai advised owners to park outside and away from structures until it is done. Check your VIN on the NHTSA recall site before you start any brake work.

Frequently Asked Questions

Can I use DOT 4 in my 2008 Elantra that calls for DOT 3?

Yes. DOT 4 is also glycol-based and compatible with DOT 3, and it has a higher minimum boiling point. For the full benefit, do a complete flush rather than just topping off.

Can I put DOT 5 in an Elantra?

No. DOT 5 is silicone-based, does not mix with the glycol fluid in the system, and is not listed by Hyundai. DOT 5.1 is a glycol fluid and is a different product; still, the safe choice is the DOT 3 or DOT 4 the manual names.

My brake fluid level is low. Should I just add more?

Check the pads first. As pads wear, the reservoir level drops naturally. If the pads are fine and the level keeps falling, you have a leak that needs to be found before you drive much further.

Is a brake fluid flush really necessary if the brakes feel fine?

Yes. Moisture lowers the boiling point long before you feel anything in normal driving. You find out on a long downhill or during a hard stop, which is the worst time. It also protects the calipers and ABS unit from internal corrosion.

How much brake fluid do I need for a flush?

Buy more than you think, since you will push fluid through at each wheel until it runs clean. Always open fresh sealed bottles; an opened bottle on the shelf keeps absorbing moisture.

Does the Elantra use the same fluid for the clutch?

Hyundai's manual refers to the fluid as brake/clutch fluid, and on manual-transmission cars the clutch hydraulics share the brake fluid reservoir, so use the same DOT 3 or DOT 4 and bleed the clutch slave when you flush.

Sources

1. Hyundai Elantra HD 2006-2010 Service Manual, Brake System Specifications - DOT 3 fluid spec, tandem master cylinder, vacuum booster, rotor sizes
2. Hyundai Elantra HD 2006-2010 Owner's Manual, Brake and Clutch Fluid - MIN/MAX check, paint damage, mineral oil and frequent top-off warnings
3. Hyundai Elantra MD Owner's Manual, Brake/Clutch Fluid - DOT 3 or DOT 4 approval
4. 49 CFR 571.116, FMVSS 116 Motor Vehicle Brake Fluids - DOT 3/4/5 boiling points, DOT 5 silicone labeling, color requirement
5. NHTSA Recall 20V-061 owner notice - ABS module recall for 2007-2010 Elantra and 2009-2011 Elantra Touring
6. Brake Fluid Explained - hygroscopic behavior, DOT 3/DOT 4 mixing, moisture pens, general replacement guideline