Mercedes-Benz GLC Maintenance Schedule (2018–2021)

Your 2018–2021 Mercedes-Benz GLC sits in the middle of the X253 first generation (2016–2022). Three engines cover this range: the 2.0L turbocharged inline-four in the GLC 300 (engine code M274, M264 from the 2020 facelift), the 3.0L twin-turbocharged V6 in the AMG GLC 43 (M276), and the 4.0L twin-turbocharged V8 in the AMG GLC 63 and GLC 63 S (M177, from model year 2018 on). Several intervals below only apply to specific engines, so check which one is under your hood before assuming a figure applies to your car.

Mercedes-Benz runs two alternating service packages on the GLC: Service A and Service B. The first Service A lands at 10,000 mi or 12 months, then Service A and B alternate every 20,000 mi or 24 months apiece, which means an A or B visit shows up roughly every 10,000 miles or 12 months. The onboard ASSYST PLUS system may call a service earlier than that under harsh operating conditions, per the booklet. For the broader Mercedes-Benz service framework this schedule sits inside, see the Mercedes-Benz maintenance schedule overview.

Oil and the Service A/B Pattern

Service A covers oil and filter, fluid checks, and a brake/tire inspection. For the GLC it also includes the dust cabin filter and a poly-V-belt check. Service B repeats the oil and filter change and adds the activated-charcoal combination cabin filter; Mercedes-Benz USA's page also lists the brake-fluid exchange under Service B.

Engine oil and filter replacement happens at every Service A and every Service B, so in practice you're looking at a change every 10,000 miles or 12 months. There's no separate severe-service oil number in the booklet. Instead, ASSYST PLUS accounts for harsher use by moving the next service reminder earlier — that's built into the normal schedule, not an add-on interval. This applies the same way across the GLC 300, GLC 43, and GLC 63.

It helps to think of Service A and Service B as one continuous 10,000-mile rhythm rather than two separate schedules. At 10,000 mi you get Service A. At 20,000 mi you get Service B, which repeats the oil and filter change and adds the cabin filter and brake fluid. Then Service A comes due again, and the two keep alternating on that same cadence. Oil and filter change every time, regardless of which letter is due.

Transmission and Drivetrain

Automatic transmission fluid service differs by engine. On the GLC 300 (M274, and M264 from the 2020 facelift) and the AMG GLC 43 (M276), it's an oil and filter change at 60,000 mi with no time limit given. The M264 four-cylinder isn't in the original MY17 booklet's engine list, but Mercedes-Benz USA's prepaid maintenance chart covers MY2015-and-newer models generically at this interval.

The AMG GLC 63 and GLC 63 S (M177, model year 2018 and later) sit on a different, generic AMG service line rather than a GLC-specific booklet entry — the MY17 booklet has no GLC 63 entry, since the car arrived for model year 2018. Mercedes-Benz USA's prepaid chart's "Specific AMG Model Services" row calls for transmission fluid at 30,000 mi, repeating at 60,000 and 90,000 mi, matching the figure the booklet gives the same M177 engine in the C-Class.

If your GLC has 4MATIC all-wheel drive, the transfer case fluid on the 9G-TRONIC (NAG3) transmission gets changed at 60,000 mi, with no time limit specified. This applies to 4MATIC-equipped cars only.

The AMG GLC 63/63 S also gets a rear differential fluid change: once at 2,000 mi, then every 30,000 mi after that. Like the transmission figure, this comes from the same generic AMG service row rather than a GLC-specific entry, and it matches the equivalent M177 service in the C-Class, where it's tied to specific option codes. The GLC 300 and GLC 43 don't carry this line in the schedule.

Taken together, the GLC's drivetrain schedule reads very differently by trim. A GLC 300 or GLC 43 owner sees the 60,000-mile transmission service and, if equipped with 4MATIC, the transfer case service at the same mileage. A GLC 63 owner sees a three-part AMG schedule in place of the 60,000-mile transmission service — transmission at 30K/60K/90K, differential fluid starting at 2,000 miles, and a shorter engine air filter interval. Don't apply one owner's schedule to another car in the lineup.

Brakes, Cooling and Spark Plugs

Brake fluid is a time-based service in the booklet: every 24 months. Mercedes-Benz USA's Service B description and prepaid chart also place the brake-fluid exchange at every Service B visit, which lines up with the same roughly-24-month cadence.

Brake inspection — a visual check of pads, linings, and disks — happens at every Service A and every Service B, so every 10,000 mi or 12 months. This is a visual check, not a fluid or part replacement on a fixed cycle of its own.

Spark plugs go 50,000 mi or 60 months across all gasoline engines, including the AMG cars. If you've seen a 40,000-mile spark plug interval mentioned for a Mercedes-Benz, that figure is an AMG row that applies only to the CLA and GLA — it doesn't apply to the GLC. Severe conditions — frequent starting and stopping, excessive idling, or sustained fast highway driving — may call for earlier replacement, per the booklet.

Engine coolant is a long-interval item: 120,000 mi or 144 months, provided the correct mixture ratio is maintained. It may need attention sooner if a non-approved coolant was ever used in the system.

Filters

The engine air filter interval depends on engine. For the GLC 300 (M274, M264 from the 2020 facelift) and the AMG GLC 43 (M276), it's 50,000 mi or 60 months — the MY17 booklet's engine list predates the M264, but Mercedes-Benz USA's prepaid chart gives the same 50K figure generically across MY2015-and-newer models. Under heavy dust, this filter may need replacement more often.

The AMG GLC 63 and GLC 63 S (M177) run on a shorter cycle: 30,000 mi, again sourced from the generic "Specific AMG Model Services" row rather than a GLC-specific booklet entry, and matching the same M177 figure in the C-Class.

The activated-charcoal cabin filter is replaced at every Service B — 20,000 mi or 24 months. The booklet also marks "replace dust filter" at every Service A and Service B for the GLC, though a footnote notes the specific interval for your country may apply. Mercedes-Benz USA's prepaid chart shows the cabin dust/combination filter only at the 20,000-mile steps. Under heavy dust or frequent recirculation use, replace it sooner.

Fuel filter service on gasoline engines is 120,000 mi or 144 months — the same long interval as the coolant. Both sit near the end of the maintenance schedule's timeline, well beyond where the Service A/B cycle repeats, so they're easy to lose track of over a decade of ownership.

Easy to Miss

A few items are easy to skip:

• The poly-V-belt visual inspection happens at every Service A (first at 10,000 mi/12 months, then every 20,000 mi/24 months) — it's not listed on the Service B table for the GLC, so don't expect it every visit.
• The GLC 63's transmission, differential, and engine air filter figures all come from a generic AMG service line rather than a GLC-specific booklet entry, since the MY17 booklet has no GLC 63 entry. The numbers match the M177's published figures in the C-Class, but they aren't GLC-specific figures.
• The transfer case fluid only applies to 4MATIC-equipped cars.
• Coolant and fuel filter both sit at 120,000 mi/144 months, well past where most owners stop tracking service history, which is exactly when they get missed.
• The AMG GLC 63/63 S engine air filter (30,000 mi) is much shorter than the GLC 300/GLC 43 interval (50,000 mi/60 months). If you're used to a non-AMG schedule and move into a GLC 63, don't carry the longer interval over.
• Brake fluid is time-based at 24 months regardless of mileage. A low-mileage GLC that's aged past two years still needs it, even if the odometer says the car barely gets driven.