2013 maintenance schedule
2013 BMW 135i Convertible Preventive Maintenance & Service Schedule
The 2013 BMW 135i Convertible is equipped with the Condition Based Service (CBS) system, a sophisticated maintenance monitoring approach that...
Last updated
September 21, 2026
Reviewed for service schedule clarity.
Key Takeaways
- The 2013 BMW 135i Convertible is powered by the turbocharged N55 3.0-liter inline-6 engine, producing 300 horsepower and 300 lb-ft of torque, and is rear-wheel drive.
- BMW's Condition Based Service (CBS) system uses sensors and algorithms to calculate individualized service intervals based on actual driving conditions, rather than applying fixed mileage to every maintenance item.
- The original 4-year/50,000-mile BMW Ultimate Service free maintenance program has long since expired for this model year.
- BMW specifies spark plug replacement at 60,000 miles for the N55 engine; for vehicles with aftermarket tuning or aggressive use, specialists recommend a shorter interval.
- Brake fluid requires replacement every two years as a fixed time-based interval critical for braking system health.
- The N55 engine has an oil capacity of approximately 6.5 liters and requires BMW Longlife-01 approved synthetic oil.
Understanding the BMW Condition Based Service (CBS) System
The 2013 BMW 135i Convertible is equipped with the Condition Based Service (CBS) system, a sophisticated maintenance monitoring approach that represents a departure from traditional fixed-interval schedules.
Sensors and special algorithms take the different driving conditions of your BMW into account to determine current and future service requirements. This means your driving style, trip length, and operating conditions all influence when service becomes due.
On the instrument cluster or Control Display, you can view remaining times or distances for:
- Engine oil service
- Front and rear brake pads
- Brake fluid
- Vehicle check
- Legally mandated inspections depending on local regulations
Your vehicle continuously stores service-requirement information in the remote control while you are driving. Your BMW Service Advisor can read this data from the remote control unit and propose an optimized maintenance approach.
Factory Maintenance Schedule
Engine Oil Service
The CBS system determines engine oil change intervals based on driving conditions rather than a fixed mileage schedule. The N55 engine has an oil capacity of approximately 6.5 liters.
Oil Specifications: The N55 engine requires BMW-approved synthetic oils meeting BMW Longlife-01 (LL-01) specifications. Approved viscosity grades include SAE 5W-30 and 5W-40.
Owner Guidance: Pelican Parts recommends changing synthetic motor oil every 5,000 miles. This conservative approach is particularly advisable for the turbocharged N55 engine, which places greater thermal stress on engine oil. BMW's flexible service intervals can range up to 10,000–15,000 miles under normal conditions. Always replace the oil filter when changing the oil.
Spark Plug Service
For the N55 engine in the 2013 135i, BMW recommends replacing spark plugs at 60,000 miles. The N55 engine uses specific spark plugs designed for turbocharged, direct-injection applications.
Owner Guidance: For modified vehicles or those with aftermarket calibrations, specialists recommend replacing spark plugs more frequently—approximately every 30,000–40,000 miles. Replacing ignition coils as preventive maintenance when performing spark plug service is also recommended.
Brake Fluid Service
BMW mandates that brake fluid be replaced every two years. This is a fixed time-based interval critical for maintaining braking performance and preventing internal corrosion in the hydraulic system.
The CBS system will also display a reminder when brake fluid service is due, but the two-year interval should be followed regardless of mileage.
Coolant Service
The cooling system capacity is approximately 8.4 liters for automatic transmission-equipped models. Specialists recommend coolant replacement every 4 years or 60,000 miles as a conservative preventive measure. Always use BMW-approved coolant to prevent corrosion and maintain cooling efficiency.
Vehicle Check
BMW specifies a comprehensive Vehicle Check as a standard scope service. This includes:
- Brake system connections and lines for leaks, damage, and correct positioning
- Underbody components including transmission, rear axle, fuel lines, and exhaust system
- Steering components for clearance, leaks, damage, and wear
- Road test with checks of brakes, steering, shock absorbers, and transmission
- Coolant level and concentration check
- Convertible-specific: Inspection of the power top hydraulic system and operation
Transmission Information
The 2013 BMW 135i Convertible is available with either a 6-speed manual or a 7-speed DCT (dual-clutch) transmission.
Manual Transmission
BMW specifies fluids conforming to MTF-LT-3 or SAF-XLS/SAF-XJ specifications with a typical viscosity of 75W-90.
DCT (Dual-Clutch Transmission)
For the DCT transmission, BMW specifies Pentosin DCTF-1 fluid. BMW considers DCT fluid a lifetime fill with no specified change interval.
Owner Guidance: Many independent specialists recommend servicing both manual and DCT transmissions at regular intervals for optimal longevity. The manual transmission is one of the most neglected service areas on a car. DCT fluid service is particularly important for maintaining smooth clutch operation and preventing premature wear.
Rear Differential
The rear differential has a fluid capacity of approximately 1.2 liters. Specialist recommendations typically suggest differential fluid service every 40,000–60,000 miles for optimal longevity.
Recommended Preventive Maintenance Summary
| Component | Factory/OEM Guidance | Preventive/Owner Guidance |
|---|---|---|
| Engine Oil | CBS-determined | 5,000 miles recommended; BMW LL-01 approved synthetic; 6.5L capacity |
| Spark Plugs | 60,000 miles | 30,000–40,000 miles for modified vehicles |
| Ignition Coils | As needed | Replace with spark plugs as preventive maintenance |
| Brake Fluid | 2 years | Fixed interval per BMW documentation |
| Coolant | As needed | 4 years or 60,000 miles (specialist recommendation); 8.4L capacity with automatic |
| Manual Transmission Fluid | As per service manual | 40,000–60,000 miles; MTF-LT-3 spec; 75W-90 |
| DCT Fluid | Lifetime fill | Specialist-recommended regular service; Pentosin DCTF-1 |
| Rear Differential Fluid | As per service manual | 40,000–60,000 miles; 1.2L capacity |
| Serpentine Belt | Inspect regularly | Replace as needed; inspect for wear/cracks |
| Vehicle Check | As per CBS | Comprehensive inspection including convertible top |
Frequently Asked Questions
How often should I change the oil on my 2013 BMW 135i Convertible?
The CBS system determines intervals based on driving conditions. Pelican Parts recommends changing synthetic motor oil every 5,000 miles. The N55 engine capacity is 6.5 liters and requires BMW LL-01 approved synthetic oil.
What engine oil should I use in my 2013 BMW 135i Convertible?
BMW recommends synthetic oils meeting Longlife-01 (LL-01) specifications. Approved viscosity grades include SAE 5W-30 and 5W-40. Always replace the oil filter when changing the oil.
When should I replace the spark plugs on my 2013 BMW 135i Convertible?
BMW recommends replacing spark plugs at 60,000 miles for the N55 engine. For modified vehicles or those driven aggressively, specialists recommend replacement every 30,000–40,000 miles. Replacing ignition coils as preventive maintenance with spark plugs is also recommended.
How often should I change the brake fluid?
Brake fluid must be replaced every two years, per BMW's factory maintenance requirements.
Does the 2013 BMW 135i Convertible require transmission fluid service?
BMW considers DCT fluid a lifetime fill with no specified interval. For the manual transmission, BMW specifies MTF-LT-3 or SAF-XLS/SAF-XJ fluids. Many specialists recommend regular service for both transmission types for optimal longevity.
When should the coolant be changed on the 2013 BMW 135i Convertible?
Specialists recommend replacing coolant every 4 years or 60,000 miles. The cooling system capacity is approximately 8.4 liters for automatic transmission models. Always use BMW-approved coolant.
What is the Condition Based Service (CBS) system?
CBS is BMW's onboard system that uses sensors and algorithms to evaluate driving conditions and calculate individual service requirements. It monitors engine oil, brake pads, brake fluid, vehicle check, and legally mandated inspections. Service data is stored in the remote control key.
What is the rear differential fluid capacity for the 2013 BMW 135i Convertible?
The rear differential has a fluid capacity of approximately 1.2 liters. Specialist recommendations typically suggest service every 40,000–60,000 miles.
What was the original warranty on the 2013 BMW 135i Convertible?
The 2013 BMW 135i Convertible came with BMW Ultimate Service, providing 48 months or 50,000 miles of free scheduled maintenance, along with 48-month unlimited-mile roadside assistance. This program has long since expired for this model year.
Are there common issues with the 2013 BMW 135i Convertible?
The N55 engine is generally considered reliable. A technical service bulletin addresses fuel system vapor formation issues in certain N55 engines, which may require low-pressure fuel pump replacement and DME software updates. Regular preventive maintenance is important for longevity.