2017-2020 Genesis G80 Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2017-2020 Genesis G80 uses brake fluid that meets FMVSS 116 DOT 3 or DOT 4, and the system holds roughly 0.74 to 0.85 US quarts (0.7 to 0.8 liters). Genesis does not print a fixed mileage for replacing it: the factory schedule calls for the fluid to be inspected every 24 months (every 15,000 miles on the 3.8 V6 and 5.0 V8, every 12,000 miles on the 3.3 twin-turbo) and replaced when that inspection finds it worn out. In practice, that means a flush about every two years for most owners.

What Brake Fluid the Genesis G80 Takes

The "Recommended Lubricants and Capacities" table in the G80 owner's manual lists brake fluid as FMVSS116 DOT-3 or DOT-4. The maintenance chapter repeats it: use only hydraulic brake fluid conforming to DOT 3 or DOT 4 specification. That covers every G80 engine sold in the US in this generation: the Lambda 3.8 GDI V6, the Lambda 3.3 T-GDI twin-turbo V6 and the Tau 5.0 GDI V8.

If you only buy one type, buy DOT 4. It meets the manual's spec and it has more margin against boiling than DOT 3 (details below). A full flush uses more fluid than the system capacity, because you push old fluid out of all four bleeders, so buy more than a quart's worth. Always open a fresh, sealed bottle. The manual warns that brake fluid exposed to open air for an extended time should never be used.

DOT 3 vs DOT 4: What the Numbers Mean

Both DOT 3 and DOT 4 are glycol-ether fluids, and federal standard FMVSS 116 sets a minimum boiling point for each. There are two numbers. The dry boiling point is for fresh fluid. The wet boiling point is measured after the fluid has absorbed 3.7 percent water by volume, which is roughly where fluid ends up after a few years in a car.

Look at how far the numbers fall between dry and wet. That drop is the whole reason brake fluid is a maintenance item. Glycol-ether fluid is hygroscopic, meaning it pulls moisture out of the air. The federal standard even requires the bottle label to tell you to keep the container tightly closed to prevent absorption of moisture. As water content climbs, the boiling point falls. On a heavy stop, such as coming down a long grade or several hard stops in a row in a full-size sedan, caliper heat can boil that water into vapor. Vapor compresses where fluid does not, and the pedal goes soft or sinks toward the floor.

DOT 3 and DOT 4 can be mixed, because they share the same glycol-ether chemistry; the blend simply has a boiling point between the two. DOT 5 is silicone and must never go into a G80. It does not mix with glycol fluid, and brake makers warn it is not suited to ABS-equipped vehicles. DOT 5.1 is a glycol fluid despite the name, but the manual only calls for DOT 3 or DOT 4, so there is no reason to use it here.

The Genesis G80 Brake Fluid Flush Interval

This is where owners get confused. In the normal maintenance schedule for the 2017-2020 G80, brake fluid is marked "I," which Genesis defines as inspect and, if necessary, adjust, correct, clean or replace. It is not marked "R" for a fixed replacement. The inspection comes up every other service:

• 3.8 GDI V6 and 5.0 GDI V8: every 15,000 miles or 24 months, whichever comes first.
• 3.3 T-GDI twin-turbo V6: every 12,000 miles or 24 months, whichever comes first.

An inspection on a car that is several years old will usually end in a replacement, because the fluid absorbs moisture whether the car is driven much or not. Brake parts maker ADVICS notes that DOT 4 usually needs replacing about every two years, and reminds owners that the owner's manual is the final word. R1 Concepts gives a similar two-to-three-year window for glycol fluids regardless of mileage. So the practical answer for a G80 is: test it at every 24-month inspection, and plan to flush it about every two years. If your G80 is a 2017 or 2018 that has never had the fluid changed, it is overdue.

The severe-usage schedule in the manual (short trips, mountain driving, heavy traffic, salted roads, towing) tells you to inspect the pads, rotors, calipers and parking brake more often. It does not list a separate brake fluid interval, but mountain driving and heavy stop-and-go are exactly the conditions that heat the fluid most, so if that is your commute, stay at the short end of the window.

Signs the Fluid Needs Attention

• Low reservoir level. The level drops slowly as the pads wear, because the caliper pistons move out and hold more fluid. The manual calls that normal. If you keep having to add fluid, the manual says that could indicate a leak. Find it before you top off again.
• Dark fluid. Fresh DOT 3 and DOT 4 is clear to light amber. Dark brown fluid is old. Color alone does not measure water content, so test it.
• Soft or sinking pedal after hard use. A pedal that fades on a long downhill and comes back once the brakes cool is the classic sign of moisture-laden fluid boiling.
• Brake warning light. Treat any red brake warning as a stop-and-check, not a top-off-and-forget.

Test strips that dip into the reservoir, or an electronic moisture tester, give a quick read on fluid condition. Either one is a better way to decide than the odometer alone.

How to Flush the Brake Fluid on a G80

A full flush is a moderate DIY job with two people, or one person with a pressure or vacuum bleeder. The G80 has disc brakes front and rear, and its ABS and stability control depend on clean fluid, which is why Genesis stresses using fluid that meets the spec to maintain braking and ABS/ESC performance.

1. Clean around the reservoir cap before you open it, so dirt does not fall in. The manual calls this out.
2. Pull most of the old fluid from the reservoir with a clean syringe and refill with fresh DOT 4 to MAX.
3. Bleed each corner until clean fluid comes out, keeping the reservoir from dropping low so you do not pull air into the system. Follow the bleed sequence in the factory service information for your drivetrain.
4. Top off to the MAX mark, cap it, and confirm the pedal is firm and high before you move the car.
5. Wipe up any spills right away, because brake fluid damages paint. Keep it out of your eyes; the manual says to flush eyes with clean water for at least 15 minutes and get immediate medical attention if it gets in.

If air gets into the ABS hydraulic unit, the system may need a scan-tool bleed procedure. If the pedal stays soft after a normal bleed, hand it to a shop that has the right tool.

Do It With the Brake Job

The easiest time to flush is when the pads or rotors are already coming off. Pushing the caliper pistons back to fit new pads forces old fluid up toward the reservoir, and bleeding the calipers afterward pushes fresh fluid through the system. For the front axle we carry 2017-2020 Genesis G80 front ceramic brake pads from Bosch. You can also browse all brake pads and brake rotors, and if a caliper piston is sticking or a hose is cracked, see our brake calipers and brake hoses. Check fitment on each listing against your G80's trim before you order, since brake sizes can vary by engine and package.

Frequently Asked Questions

Does the Genesis G80 use DOT 3 or DOT 4 brake fluid?

Either. The owner's manual specifies FMVSS 116 DOT 3 or DOT 4. DOT 4 is the better pick because its minimum dry and wet boiling points are higher.

How often should I change the brake fluid on a 2017-2020 G80?

Genesis schedules a brake fluid inspection every 24 months (15,000 miles on the 3.8 and 5.0, 12,000 miles on the 3.3T) with replacement as needed. Most owners should plan on a flush about every two years.

How much brake fluid does a Genesis G80 hold?

The manual lists 0.74 to 0.85 US quarts (0.7 to 0.8 liters). Buy extra for a full flush, since you push fluid out of each bleeder.

Can I mix DOT 3 and DOT 4 in my G80?

Yes. Both are glycol-ether fluids and are compatible, though the mix performs somewhere between the two. Never add DOT 5 silicone fluid.

Why is my G80 brake fluid level going down?

A slow drop is normal as the pads wear. Needing to add fluid often points to a leak somewhere in the lines, hoses or calipers, and the car should be inspected before it is driven much further.

Sources

1. Genesis - 2019 G80 Owner's Manual - DOT 3 or DOT 4 spec, 0.7-0.8 L capacity, inspection intervals by engine, severe-usage schedule, reservoir and safety warnings
2. Genesis - 2018 G80 Quick Reference Guide - brake fluid inspection at 15,000 miles/24 months (3.8L/5.0L) and 12,000 miles/24 months (3.3T)
3. 49 CFR 571.116, FMVSS No. 116 Motor Vehicle Brake Fluids - minimum dry and wet boiling points for DOT 3, DOT 4 and DOT 5; keep-container-closed label requirement
4. ADVICS - Brake Fluid Boiling Points - wet boiling point at 3.7 percent water, hygroscopic glycol fluid, DOT 4 replacement about every two years
5. R1 Concepts - Brake Fluid Types Explained - DOT 3/4 compatibility, DOT 5 silicone warnings, two-to-three-year change window