2008-2015 Mercedes-Benz C63 Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

Every 2008-2015 Mercedes-Benz C63 AMG takes brake fluid that meets Mercedes-Benz specification MB 331.0, sold by Mercedes as DOT 4 PLUS. Mercedes dealers replace it every 2 years or 20,000 miles, whichever comes first, as part of Service B. If you track the car or drive it hard in the hills, flush it more often than that.

What MB 331.0 Brake Fluid Is

Mercedes-Benz publishes an approved-fluids sheet for brake fluid under the number 331.0. Its stated application area is all Mercedes-Benz passenger cars and vans, which covers both the W204 C63 AMG with the 6.2-liter V8 and the W205 C63 with the 4.0-liter twin-turbo V8. The genuine product listed on that sheet is Mercedes part A 000 989 56 05.

Mercedes' own safety data sheet for its "Brake fluid DOT4 PLUS, MB 331.0" describes it as a technical mixture of polyglycol ethers, polyglycols and their borate esters, plus amines, additives and stabilizers. In plain terms, it is a glycol-based fluid in the same chemical family as ordinary DOT 3, DOT 4 and DOT 5.1 fluid, not a silicone DOT 5 fluid.

What separates a "DOT 4 plus" or low-viscosity fluid from a basic DOT 4 is how easily it flows when cold. Penrite's brake fluid technical sheet notes that a fluid whose viscosity is high at low air temperatures can hurt ABS performance, and that fluids not meeting current specs can lead to malfunctioning ABS and ESP systems. The C63 relies on ABS and ESP modulation on every hard stop, so the fluid spec is not a place to cut corners.

How the DOT Ratings Compare

All brake fluid sold in the U.S. has to meet FMVSS 116. The key numbers are the dry boiling point (fresh fluid) and the wet boiling point (fluid carrying 3.7 percent water by volume, which Penrite describes as typical after 1-2 years of use). These are the minimums from Penrite's published specification table:

Those are floors, not what a given bottle delivers. The point for a C63 owner is the gap between the dry and wet columns: as the fluid picks up water, its boiling point drops sharply, and a car with this much power and weight puts a lot of heat into its calipers. Penrite notes that pads can reach around 300 C and that heat soaking through the caliper can push fluid temperature past 200 C.

Why the 2-Year Flush Interval Matters on a C63

Glycol-based brake fluid is hygroscopic: it pulls moisture out of the air through the reservoir cap, seals and hoses whether the car is driven or not. That is why the Mercedes interval is time-based as well as mileage-based. Fletcher Jones Mercedes and Mercedes-Benz of Novi both describe the factory schedule as brake fluid exchange every 2 years or 20,000 miles, done within Service B. Textar, a major OE brake supplier, also recommends changing brake fluid every two years.

When wet fluid boils in the caliper it forms vapor bubbles. Vapor compresses where fluid does not, so the pedal goes long or soft in the middle of a stop. Moisture also promotes internal corrosion in lines, caliper bores and the ABS unit, which is far more expensive to fix than a flush.

Penrite's guidance by driving style is a useful way to think about a C63:

• Daily driving: the 2-year / 20,000-mile factory interval.
• Spirited driving on winding roads: every six months to a year.
• Track days: fresh fluid before each event.

Signs Your C63 Brake Fluid Is Overdue

• Soft or long pedal after repeated hard stops that firms back up once the brakes cool. That is classic fluid fade.
• Dark, cloudy fluid in the reservoir. Fresh DOT 4 PLUS is light amber.
• No record of a flush in the last two years, or a used car with no service history.
• A service reminder for Service B on the instrument cluster.
• Low reservoir level: usually worn pads (the caliper pistons sit further out), but also check for leaks at hoses and calipers before topping off.

Color is only a rough guide. A shop can test moisture content or boiling point directly, but on a car on the factory schedule the calendar is what decides it.

How the Flush Is Done and What to Replace With It

Mercedes dealers use pressure bleeding equipment and approved DOT 4 PLUS fluid. The job pushes new fluid through each caliper until clean fluid comes out, working from the wheel farthest from the master cylinder. A full flush replaces the fluid in the lines and calipers, not just the reservoir. On a car with ESP, some procedures call for a scan tool to cycle the ABS pump; follow the factory service information for your exact model.

A few practical rules:

• Do not mix fluid types casually. Penrite notes DOT 3, DOT 4 and DOT 5.1 glycol fluids are miscible but mixing is not recommended, and silicone DOT 5 must never be mixed with them. Topping up old fluid with new just dilutes the new fluid with water-laden old fluid.
• Use a sealed, fresh bottle. An opened bottle sitting on a shelf absorbs moisture too.
• Pair it with a pad or rotor job. Pushing caliper pistons back for new pads is the ideal time to flush. For the W204 C63 we carry EBC Redstuff front brake pads for the 2008-2013 C63 AMG and EBC Redstuff rear pads for the W204 6.2L. For the W205, see the EBC Redstuff ceramic front pads for the W205 C63 twin-turbo.
• Track cars: fresh high-boiling-point fluid pairs with a track compound such as the EBC Bluestuff NDX front pads for the W204 C63. Browse more options in our brake pads and brake rotors collections.
• Inspect the flexible hoses while the wheels are off. Cracked or swollen hoses should be replaced; see our brake hoses.

A home flush is a moderate job for someone comfortable with jack stands and a pressure or vacuum bleeder. The main risks are letting the reservoir run dry and drawing air into the ABS unit, and spilling fluid on paint, which it damages. If you are unsure about the ESP bleed procedure, have a shop with the right scan tool do it.

Frequently Asked Questions

What brake fluid does a 2008-2015 Mercedes C63 AMG take?

Fluid that meets Mercedes-Benz spec MB 331.0, sold as DOT 4 PLUS. Mercedes' 331.0 sheet applies to all Mercedes-Benz passenger cars and vans, which includes both the W204 and W205 C63.

How often should I flush the brake fluid on my C63?

Mercedes dealers do it every 2 years or 20,000 miles, whichever comes first, as part of Service B. Flush more often if you drive aggressively, and before every track day.

Can I use regular DOT 4 in a C63?

Mercedes specifies an MB 331.0 approved fluid. A generic DOT 4 only has to meet the FMVSS 116 minimums, which allow higher cold viscosity than a low-viscosity fluid. Use an MB 331.0 approved fluid to match what the ABS and ESP systems were designed around.

Can I mix DOT 4 PLUS with DOT 3 or DOT 5.1?

They are all glycol-based and technically miscible, but mixing is not recommended. Never add silicone DOT 5 fluid to a C63; it is not compatible with glycol fluids.

Why does my C63 pedal go soft on a mountain road but feel normal the next day?

That is typically boiled fluid. Water in old fluid lowers its boiling point, and heavy braking heats it until vapor forms in the calipers. Once it cools, the vapor condenses and the pedal returns. A fresh flush is the fix.

Sources

1. Mercedes-Benz Operating Fluids - Sheet 331.0 Brake Fluid - 331.0 applies to all Mercedes-Benz passenger cars and vans; genuine part A 000 989 56 05
2. Mercedes-Benz Safety Data Sheet - Brake fluid DOT4 PLUS, MB 331.0 - polyglycol ether and borate ester composition
3. Penrite - Understanding Brake Fluids - FMVSS 116 boiling points and viscosity, wet boiling point definition, mixing guidance, intervals by driving style
4. Fletcher Jones Motorcars - Mercedes-Benz Brake Fluid Replacement - 2 years or 20,000 miles within Service B
5. Mercedes-Benz of Novi - Brake Fluid Flush Every 2 Years or 20,000 Miles - interval and moisture effects
6. Textar - Brake Fluid - brake fluid change every two years