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2018 Mercedes Benz Gls Class Maintenance Schedule

Manufacturer-recommended service intervals for the ASSYST Plus (Service A / Service B) and open recall alerts for your 2018 Mercedes Benz Gls Class.

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RecallsFull scheduleKnown issues5

How Mercedes-Benz schedules service: ASSYST Plus (Service A / Service B)

Mercedes-Benz alternates two service events: Service A (oil, filter, inspection) at roughly 10,000 miles or 1 year, then Service B (Service A plus brake fluid, cabin filter, and deeper checks) at roughly 20,000 miles or 2 years — the ASSYST Plus counter in the cluster tells you which is due. Oil must carry the MB-Approval number your engine specifies (commonly 229.5, or 229.71 for newer 0W-20 engines); 'meets or exceeds' marketing language is not an approval. Electric EQB and EQS models keep the A/B rhythm for inspections, brake fluid, and cabin filters — just without oil.

Essential maintenance

Critical for safety and preventing major damage

🛢️

Service A — Oil & Filter + Inspection

Every 10,000 mi

Every 10,000 miles or 12 months: oil and filter with MB-Approved oil, fluid top-offs, tire check, and inspection. AMG models driven hard: many owners service at 5,000-7,500 miles.

Estimated cost — typical U.S. ranges

Dealer

~$120–$160

Shop

~$85–$115

DIY

~$25–$55

Full synthetic costs more than conventional. 5-quart 0W-20 + filter is the typical bill.

🔍

Service B — Major Inspection

Every 20,000 mi

Every 20,000 miles or 2 years, alternating with Service A: everything in A plus brake-fluid replacement, cabin filter, and a deeper multi-point inspection of brakes, suspension, and driveline.

Estimated cost — typical U.S. ranges

Dealer

~$85

Shop

~$60

DIY

Free

Most shops do this free with any paid service. A flashlight and 10 minutes covers the basics yourself.

🔄

Tire Rotation

Every 10,000 mi

Rotate at every Service A where the tire sizes allow. Many AMG and 4MATIC+ models run staggered widths that can't rotate front-to-rear — check your spec before paying for a rotation.

Estimated cost — typical U.S. ranges

Dealer

~$85

Shop

~$60

DIY

Free

Often free at the shop where you bought the tires — worth asking before paying.

🛑

Brake Inspection

Every 10,000 mi

Checked at every A/B service via electronic pad-wear sensors. Replace sensors with pads. Heavy EQS models wear pads slowly (regen braking) but rotors can corrode from disuse — an inspection catches that.

Estimated cost — typical U.S. ranges

Dealer

~$85

Shop

~$60

DIY

Free

Most shops do this free as a courtesy with any service. Don't pay separately if you can avoid it.

🧪

Brake Fluid

Every 20,000 mi

Replaced every 2 years as part of Service B — Mercedes schedules it on time, not miles, because DOT 4 fluid absorbs moisture regardless of driving.

Estimated cost — typical U.S. ranges

Dealer

~$180–$200

Shop

~$125–$140

DIY

~$10–$25

DOT 3 or 4 — match the cap. Vacuum bleeders make this a one-person DIY.

Important maintenance

Keeps your vehicle running smoothly and efficiently

⚙️

Automatic Transmission Fluid (7G / 9G-Tronic)

Every 70,000 mi

Mercedes specifies fluid and filter service around 70,000 miles on most 7G- and 9G-Tronic gearboxes — check your year's sheet. Use only the MB-spec fluid for your transmission code; independent specialists often service at 60,000 on hard-driven cars.

Estimated cost — typical U.S. ranges

Dealer

~$330–$500

Shop

~$235–$355

DIY

~$60–$180

Some sealed transmissions have no dipstick — fill is precise and best left to a shop. Many drivers can still DIY drain-and-fill.

⚡

Spark Plugs

Every 60,000 mi

Most modern MB gas engines: plugs around 60,000 miles — AMG engines often sooner. Check your engine's sheet; twin-turbo V8 plug jobs are labor-heavy, so pair with other scheduled work.

Estimated cost — typical U.S. ranges

Dealer

~$285–$390

Shop

~$200–$275

DIY

~$25–$100

Iridium plugs cost more but last 100k+ miles. V6/V8 access varies wildly — some are tough.

💨

Engine Air Filter

Every 40,000 mi

Replace around every 40,000 miles (twin-filter setups on V6/V8 engines double the parts bill). Inspected at every Service B.

Estimated cost — typical U.S. ranges

Dealer

~$60–$95

Shop

~$45–$70

DIY

~$15–$40

5-minute job on most cars; the airbox lid usually has clips, no tools needed.

Recommended maintenance

Extends the life of your vehicle and improves comfort

🌬️

Combination / Dust Filter

Every 20,000 mi

Replaced with every Service B. Models with the ENERGIZING air package use a higher-grade filter — priced accordingly.

Estimated cost — typical U.S. ranges

Dealer

~$60–$95

Shop

~$45–$70

DIY

~$15–$40

Usually behind the glovebox. Shops charge labor for a 10-minute job — easy DIY win.

🌡️

Engine Coolant

On condition / lifetime

MB-spec coolant is long-life (typically ~10 years / 150,000 miles on the sheet). Refresh only with MB 325/326-spec coolant — the wrong chemistry attacks aluminum and head gaskets.

Estimated cost — typical U.S. ranges

Dealer

~$285–$330

Shop

~$200–$235

DIY

~$25–$60

Use the manufacturer-specified coolant — wrong color/chemistry can damage the cooling system.

🔋

12V & Auxiliary Battery

Every 25,000 mi

Test annually after year 3. Most modern Mercedes carry a second auxiliary battery; a weak one triggers cascading warning messages long before a no-start. EQ models also depend on the 12V system to boot.

Estimated cost — typical U.S. ranges

Dealer

~$225–$390

Shop

~$160–$280

DIY

~$130–$250

Most auto-parts stores test and install batteries free with purchase. Skip the dealer markup.

Known issues for this vehicle

What drivers and federal regulators have officially reported about the 2018 Mercedes Benz Gls Class.

Reported to NHTSA

Panoramic sunroof glass panel shattering

STRUCTURE

3 NHTSA complaints · 2018-11 → 2022-03

“While driving our 2018 Mercedes GLS 450 down Highway 80 just outside Sacramento, CA, the stationary glass panel of our panoramic sunroof spontaneously explpoded. There was no impact by any outside force, it just shattered with the sound similar to a gunshot…”
— Owner report, NHTSA ODI #11457706
“I WAS DRIVING IN A RURAL AREA WHEN ALL OF A SUDDEN I HEARD WHAT SOUNDED LIKE AN EXPLOSION. MY FIRST INSTINCT WAS THAT I HAD BLOWN A TIRE BECAUSE IT WAS SO LOUD. HOWEVER, THE CAR WAS HANDLING FINE AND NO WARNING MESSAGES CAME ON. MY HUSBAND AND I BOTH SAID "WHAT WAS THAT?"…”
— Owner report, NHTSA ODI #11154785

Read all complaints on NHTSA →

Brake system failure to stop vehicle

SERVICE BRAKES

4 NHTSA complaints · 2020-09 → 2025-08

“Brake brakes are terrible. They have other years that they’ve acknowledge that the break are spongy and at times does not break the GLS has that defect. Also smell of gas fumes inside the vehicle. Please direct me the right way and help me with this issue…”
— Owner report, NHTSA ODI #11683217
“I WAS ALREADY 90% IN PARKING LINE WHICH IS HANDICAP'S. ABOUT TO STOP RIGHT FRONT OF HANDICAP SIGN, SUDDENLY VEHICLE START MOVING FORWARD WHILE MY FOOT WAS IN BRAKE SO I PUSH LITTLE HARD TO COMPLETE STOP BUT VEHICLE SUDDENLY ACCELERATE FORWARD SMASHING INTO THE BUILDING…”
— Owner report, NHTSA ODI #11353649

Read all complaints on NHTSA →

Suspension system malfunction

SUSPENSION

3 NHTSA complaints · 2025-04 → 2026-07

“The contact owns a 2018 Mercedes-Benz GLS 550. The contact stated while driving at various speeds, the vehicle made an abnormal clicking sound when making a right turn, and an abnormal ticking sound at startup. There was no warning light illuminated.…”
— Owner report, NHTSA ODI #11748540
“When attempting to rise/lower the automatic suspension, the compressor cooling notification pops up, followed by a malfunction. After this occurs, the vehicle is incredibly bumpy, to the point of it being unsafe to drive.…”
— Owner report, NHTSA ODI #11656041

Read all complaints on NHTSA →

Uncommanded shift into neutral

POWER TRAIN

2 NHTSA complaints · 2018-06 → 2018-11

“I FOUND OUT THAT ONLY ON 2018 MERCEDES GLS MODELS, THE CAR LETS YOU TURN OFF THE ENGINE WITHOUT A WARNING AND PUTS THE CAR IN NEUTRAL AUTOMATICALLY. IT DOES NOT PUT THE CAR TO 'P' OR GIVES YOU A WARNING SAYING YOU NEED TO PUT THE GEAR TO 'P' TO STOP THE CAR.…”
— Owner report, NHTSA ODI #11150448
“WHILE IN MOTION ON A HIGHWAY IN STOP AND GO TRAFFIC, CAR SHIFTED ITSELF FROM DRIVE TO NEUTRAL WITHOUT ANY DRIVER INPUT. ALL INDICATOR LIGHTS ON DASH TURNED ON. DRIVER UNABLE TO SHIFT FROM NEUTRAL BACK TO DRIVE TO REGAIN CONTROL OF VEHICLE. DRIVER COULD ONLY SHIFT TO PARK.…”
— Owner report, NHTSA ODI #11101953

Read all complaints on NHTSA →

Engine compartment fire

ENGINE

3 NHTSA complaints · 2018-08 → 2025-12

“The contact owned a 2018 Mercedes Benz GLS450. The contact stated that after turning the ignition switch off, the driver suddenly discovered flames were coming from the engine compartment. The fire department was called to the scene and extinguished the flames.…”
— Owner report, NHTSA ODI #11436804
“January 2023 - Airbag suspension failed. Replaced by Mercedes dealership. December 2024 - Airbag suspension failed. Replaced by Mercedes dealership. April 2024: First brake failure. The brakes stopped while driving. Repaired.…”
— Owner report, NHTSA ODI #11703281

Read all complaints on NHTSA →

Issues on other model years

  • 2016 Mercedes Benz Gls Class →
  • 2017 Mercedes Benz Gls Class →
  • 2019 Mercedes Benz Gls Class →
  • 2020 Mercedes Benz Gls Class →
  • 2021 Mercedes Benz Gls Class →
  • 2022 Mercedes Benz Gls Class →

Source: NHTSA Office of Defects Investigation (ODI). Complaint data refreshed Jul 27, 2026. Investigation data refreshed Jul 27, 2026.

We display NHTSA's record with attribution; we don't editorialize on what these complaints mean for any specific vehicle.

Typical U.S. ranges. Actual quotes vary by shop, parts choice, and vehicle condition.

How we estimate: Dealer = OEM parts × 1.4 + labor × $165/hr. Shop = parts + labor × $115/hr. DIY = parts only.

This maintenance schedule for the 2018 Mercedes Benz Gls Class reflects Mercedes-Benz's published service intervals and the ASSYST Plus (Service A / Service B) system. Your actual service needs may vary based on driving conditions, climate, and vehicle usage. Always consult your owner's manual for model-specific recommendations.

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