2016 BMW i3 REX Preventive Maintenance & Service Schedule

Key Takeaways

• The 2016 BMW i3 REX combines an electric motor with a 650cc two-cylinder range extender engine that requires periodic maintenance, including engine oil and filter changes, despite the engine not driving the wheels directly .
• Engine oil and filter should be changed approximately every 10,000 miles or 12 months, as determined by BMW's Condition Based Service system; the REX engine takes approximately 2.6 liters of oil .
• Brake fluid must be replaced every 2 years regardless of mileage due to moisture absorption, which can compromise braking system safety and performance .
• Spark plugs and engine air filter are "long-term rated" and do not require periodic replacement according to BMW's official documentation, due to the REX engine's light-duty operating conditions .
• Service mode activation is required for certain maintenance procedures; this mode can be activated manually when the battery state of charge is below 75% .
• A Safety Recall (17V-088) affects certain 2014-2017 i3 REX models for inspection and potential replacement of the fuel tank vent line; owners should verify their vehicle's recall status .
• REX-specific cooling system components should be inspected periodically, as coolant expansion tank leaks have been identified in some vehicles .

Understanding the 2016 BMW i3 REX

The 2016 BMW i3 with Range Extender pairs a high-voltage battery and electric motor with a 650cc two-cylinder engine derived from a BMW scooter. This engine does not drive the wheels; it functions as a generator to recharge the battery, extending the vehicle's range. Because the REX engine operates under light and relatively constant loads, BMW's official documentation indicates that the spark plugs and engine air filter are "long-term rated" and do not need periodic replacement—a notable exception compared to conventional gasoline vehicles .

BMW's Condition Based Service (CBS) system monitors actual vehicle usage—including driving conditions and engine operating hours—to determine maintenance needs. Service reminders are displayed through the vehicle's information center . This system tailors maintenance timing to how the vehicle is actually driven, meaning two identical vehicles may show different service due dates based on their unique usage patterns.

Engine Oil and Filter Change

Factory Schedule

The REX engine requires oil changes at intervals determined by the CBS system, typically around 10,000 miles or 12 months . BMW's official service documentation confirms that REX engine oil and filter service is included in the maintenance schedule .

Oil Capacity and Specification:

• Capacity: Approximately 2.6 liters for a service fill
• Recommended Oil: 5W-30 or 5W-40 synthetic oil meeting BMW's specifications

Owner Guidance: Given the extended intervals between REX engine use, some owners choose to change the oil annually as a conservative measure. Forum discussions note that a 2-year interval may be applicable in some markets, but the CBS system is the authoritative source for your specific vehicle . Always replace the oil filter when changing the oil.

Important Safety Note: BMW recommends deactivating the high-voltage system before performing maintenance on the REX engine. The i3 features a service mode that can be activated when the battery state of charge is below 75% using diagnostic tools, or accessed manually for certain maintenance tasks .

Brake Fluid Replacement

BMW requires brake fluid replacement every 2 years for the i3, including the REX variant . The brake fluid must meet DOT4 specification .

Why 2 Years: Brake fluid absorbs moisture over time, which can lower its boiling point and cause internal corrosion in brake system components. The 2-year interval is a conservative safety standard to ensure braking system integrity .

Owner Guidance: A brake fluid flush for the 2016 i3 REX typically costs approximately £43 for a DIY service, with the correct wheel lug nut torque specification being 140 N⋅m (103 ft⋅lb) . Some owners report switching to a 3-year schedule using Bosch extended-life fluid, but the 2-year BMW recommendation remains the safest approach .

Vehicle Inspection

BMW's official documentation for the i3 REX includes a "Fahrzeug-Check" (vehicle check) performed according to the BMW i Service Schedule . This inspection is generally performed at the same 2-year interval as the brake fluid service and includes a comprehensive multi-point inspection of the vehicle .

Service Items Not Required

Spark Plugs

BMW's official U.S. maintenance document confirms: "Due to the light duty and relatively constant operating speeds, the range extender engine's spark plugs and air filter are long-term rated, which do not need periodic replacement" .

Engine Air Filter

The engine air filter is also "long-term rated" and does not require periodic replacement under normal operating conditions .

Cooling System

REX-Specific Coolant

The REX model has a third cooling circuit that transfers heat from the REX engine to the main propulsion cooling system . Unlike brake fluid, there is no recommended cooling fluid change interval . However, BMW has issued a Technical Service Bulletin addressing a potential issue where a leaking coolant expansion tank can trigger a check control message: "DRIVETRAIN: only electric drive possible" .

Owner Guidance: While periodic coolant replacement is not required, the coolant level should be checked periodically and topped up with BMW-approved coolant containing HT-12 Anti-Corrosion Agent if necessary. The coolant expansion tank and connecting hoses should also be inspected for damage .

REX Service Mode and Maintenance Cycle

Service Mode Activation

Service mode must be activated for certain maintenance procedures, including brake service and suspension work . Service mode can be activated:

• Using a diagnostic tool such as YOUCAN-II
• Manually by following the procedure: pressing the Start-Stop button (without pressing pedals) to switch on the ignition, then holding the trip distance recorder reset button for approximately 10 seconds

REX Maintenance Cycle

The REX engine automatically performs a self-maintenance cycle if it has not been used for an extended period—typically around 2 to 3 months . During this cycle, the REX engine runs for approximately 10 minutes to lubricate internal components and ensure proper operation . This is a normal function and does not require user intervention.

Summary Maintenance Schedule

Important Recalls and Service Actions

Safety Recall 17V-088: Fuel Tank Vent Line

This recall affects certain 2014-2017 BMW i3 REX models produced between March 2014 and December 2016 . The issue involves a section of the fuel tank vent line adjacent to the positive battery cable sleeve that may wear through over time, potentially causing a fuel vapor leak and increasing fire risk . The repair includes inspecting the fuel tank vent line and replacing it if damaged, and attaching a clip between the vent line and B+ cable to prevent contact . Approximately 19,130 U.S. vehicles are potentially affected . Owners should verify whether this recall has been completed on their vehicle.

Service Action: Motor Mount Screws

A Service Action (SI B22 01 15) addresses the replacement of motor mount screws on i3 and i3 REX models produced from October 2013 to November 2015 . A sudden loss of traction while accelerating sharply may damage the engine mounts, requiring replacement of the mount screws . This action applies to both left and right side mounts on the REX variant .