BMW 3 Series Maintenance Schedule (G20, 2019–2026)

The 2019–2026 BMW 3 Series (G20) doesn't follow a fixed mileage chart. BMW's Condition Based Service (CBS) system tells you when the oil is due, at most every 10,000 miles (≈16,000 km) or 12 months, and almost everything else on the US schedule is counted in oil services: the cabin microfilter every 2nd (about 20,000 miles, ≈32,000 km), the spark plugs every 6th (about 60,000 miles, ≈97,000 km). Brake fluid runs on a 24-month clock. Coolant, the automatic transmission and the xDrive transfer case have no scheduled change at all.

This guide covers the 330i, M340i and 330e of the G20 generation sold in the US for model years 2019 through 2026, using BMW of North America's maintenance booklet for each of those years. It does not cover 3 Series cars built before the 2019 model year, whose schedules we haven't reviewed.

Quick reference: the G20 3 Series schedule

Item	What BMW says	When
Engine oil and filter	Change	When CBS calls for it; at most 10,000 miles (≈16,000 km) or 12 months
Cabin microfilter	Replace	Every 2nd oil service, about 20,000 miles (≈32,000 km)
Engine air filter	Replace	40,000 miles (≈64,000 km) for MY2021, 2022 and 2024; 30,000 miles (≈48,000 km) for MY2023 and 2026
Spark plugs	Replace	Every 6th oil service, about 60,000 miles (≈97,000 km)
Brake fluid	Replace	Every 24 months, when CBS shows it due
Brake pads and discs	Monitored by CBS	Pads replaced when displayed; discs checked at that service
Coolant, automatic transmission, xDrive transfer case	No scheduled change	Long-term rated fluids

The engines behind these numbers are the 2.0L TwinPower Turbo four-cylinder (B46/B48) in the 330i and 330i xDrive, the 3.0L TwinPower Turbo inline-six (B58) in the M340i and M340i xDrive from 2020, and the 2.0L plug-in hybrid in the 330e and 330e xDrive. The schedule above is the same for all of them unless a row says otherwise.

How Condition Based Service decides when

CBS is BMW's own term for the service reminder in the car. The display tracks the engine oil by date and mileage, the brake fluid by date, and the front and rear brake pads by their remaining wear. For cars produced from July 2013 onward, BMW's service information sets the CBS engine oil interval at no more than 10,000 miles or 12 months, whichever comes first.

The display can call for oil sooner than that. BMW names the conditions that bring it forward: short trips, cold starts, idling and high engine speeds. If most of your driving looks like that, expect the reminder to arrive well before the maximum.

Several items never show up on the display. The cabin microfilter, the engine air filter and the spark plugs are tied to the oil service count instead, and they are done together with an oil service. That's why it pays to keep a record of how many oil services the car has had.

Engine oil, filters and spark plugs

Engine oil and filter. Change them when CBS asks, and don't go past 10,000 miles (≈16,000 km) or 12 months. The booklets list it as "change engine oil and oil filter" for all models.

Cabin microfilter. BMW calls it the ventilation microfilter and replaces it at every 2nd engine oil service, about 20,000 miles (≈32,000 km), in every model year from 2019 to 2026.

Engine air filter. This is the one item that moves between booklets, so check your model year:

• MY2021, 2022 and 2024: every 4th oil service, about 40,000 miles (≈64,000 km).
• MY2023: the booklet marks the filter at both the 3rd and the 4th oil service. Replacing it at about 30,000 miles (≈48,000 km) satisfies both.
• MY2026: every 3rd oil service, about 30,000 miles (≈48,000 km).
• MY2019, 2020 and 2025: the booklets give no single interval for the 330i, M340i or 330e, so we don't state one. Follow your own booklet or ask a BMW service advisor.

In every year, BMW says to replace the air filter more often in dusty conditions.

Spark plugs. Replace them at every 6th engine oil service, about 60,000 miles (≈97,000 km). The booklets list this for all non-M models, with no time limit.

Brakes and brake fluid

BMW treats brakes as a condition item, not a mileage item. The front and rear pads are monitored by CBS, which shows the remaining miles; the pads are replaced when the display calls for them, and the discs are checked for surface and thickness at that service and replaced as necessary. The brake lines and connections are checked for leaks at each CBS vehicle check.

Brake fluid is purely time-based. Replace it when the CBS display shows it due, which is every 24 months after each change. The first change can be scheduled later than that, because it may be counted from the car's production date rather than the day you bought it.

Long-life fluids: coolant, transmission and transfer case

BMW's booklets list these as long-term rated fluids. The factory fill is meant to stay in, and BMW says replacement is only necessary when repairs are performed:

• Engine coolant. No scheduled replacement. The coolant level and concentration are checked at each CBS vehicle check.
• 8-speed automatic transmission. No scheduled fluid change.
• xDrive transfer case. No scheduled fluid change, unless the car's own service system calls for one.

The same booklets give no rear differential fluid interval for the non-M 3 Series. There is no row for it in the schedule and it isn't on the long-term list either, so BMW makes no statement about it.

What BMW doesn't schedule for the 3 Series

A few items that generic checklists include have no interval in BMW's US booklets for the G20:

• Tire rotation. No booklet gives a rotation interval, and many cars run staggered tire sizes.
• 12V battery. The only item is "check state of charge and charge, if required" inside the CBS vehicle check. There is no replacement interval.
• 330e high-voltage battery coolant. BMW lists a check of the coolant level and concentration in both reservoirs as part of the vehicle check, and no replacement interval.

If a shop quotes one of these as "factory scheduled" for a G20, ask which BMW document it comes from.