- Aluminum alloy block and head with DOHC and timing chain
- Turbo with variable-geometry turbine and water-cooled intercooler for fast response
- High-pressure common-rail injectors support up to four injections per cycle
- EGR includes low- and high-pressure systems with i-ELOOP regeneration
Mazda’s 1.5-liter SkyActiv-D turbo-diesel engines, technically identified as S5-DPTR and S5-DPTS, represent Mazda’s contribution to the small, efficient diesel engine segment. These engines were developed under the Japanese manufacturer’s SkyActiv-D umbrella and were offered optionally with an innovative active regeneration system that integrates Intelligent Energy Loop (i-ELOOP) braking technology for recovering kinetic energy.
These powertrains were designed for Mazda’s compact models, offering an appealing balance between efficiency and performance for both urban and highway use.
Architecture and technical solutions
Block construction and timing system
The 1.5 SkyActiv-D engines feature a modern aluminum alloy cylinder head and camshafts (DOHC) driven by a timing chain. Each cylinder has four valves actuated by rocker arms, a system that blends mechanical simplicity with reduced friction losses. The engine block is also made from aluminum, contributing to a lower overall mass and aiding in fuel efficiency and vehicle dynamics.
Turbocharging and intake system
A key element of this engine’s performance is the compact turbocharger equipped with a variable-geometry turbine (VGT). This system allows the turbine vanes to adjust based on engine speed and power demand, providing a faster throttle response and a broad, flat torque curve.
Air is cooled by a water-cooled intercooler, integrated directly into the plastic intake plenum. This design enables more efficient intake air cooling than air-cooled systems, resulting in higher air density and more efficient combustion.
Injection and combustion system
The engine uses high-pressure common-rail solenoid injectors capable of multiple injections within a single combustion cycle. To stabilize the combustion process and reduce diesel-specific noise, fuel can be injected up to four times per cycle:
- Pilot injection (pre-injection) – to pre-warm the combustion chamber
- Main injection – to generate power
- Post-injection events – for emissions control and to regenerate the particulate filter
This multi-injection strategy promotes a more progressive combustion, reducing the characteristic diesel clatter and improving emission performance.
Optimized cooling system
The cooling system for the 1.5 SkyActiv-D includes coolant valves (CCV - Coolant Control Valve). This technology enables intelligent temperature management, accelerating warm-up at cold starts and maintaining the optimal operating temperature under varying conditions.
The engine block also features special spacers for the cooling circuit that optimize coolant flow around the cylinders. This contributes to:
- Improved combustion efficiency by maintaining optimal temperatures
- Reduced mechanical resistance
- Uniform temperature distribution across the entire engine block
Emission control – EGR system
To meet emissions standards, the 1.5 SkyActiv-D is equipped with both low-pressure and high-pressure exhaust gas recirculation (EGR) systems. This double configuration helps:
- Lower combustion temperatures and NOx emissions
- Maintain adequate intake pressure at high loads
- Improve efficiency across varied operating conditions
Complete technical specifications
General data:
- Manufacturer: Mazda Motor Corporation
- Production period: 2015–present
- Engine code: S5-DPTR, S5-DPTS
- Cylinder block material: Aluminum alloy
- Cylinder head material: Aluminum alloy
- Fuel type: Diesel
- Fuel system: Direct injection, common-rail
Configuration:
- Architecture: Inline-four
- Number of cylinders: 4
- Valves per cylinder: 4
- Total valves: 16
- Valvetrain: DOHC (Double Overhead Camshaft)
- Drive: Timing chain
Dimensions and capacity:
- Bore: 76.0 mm
- Stroke: 82.5 mm
- Displacement: 1497 cm³ (1.5 L)
- Compression ratio: 14.0:1
Performance:
- Maximum power: 105 hp (77 kW) at 3500–4500 rpm
- Maximum torque: 220–270 Nm at 1600–2500 rpm
- Forced induction: Variable-geometry turbocharger (VGT)
- Intercooler: Water-cooled, integrated into the intake manifold
Lubrication requirements:
- Recommended oil grade: 0W-30
- Engine oil capacity:
- Service fill: 5.1 liters
- Dry (engine fully drained): 5.8 liters
- Oil filter: 0.4 liters
- Oil change interval: 20,000 km or 12 months (whichever comes first)
Applications:
- Mazda 2 (DJ/DL generation)
- Mazda CX-3 (DK generation)
Known issues and reliability considerations
Oil level concerns
One of the most commonly reported issues for the 1.5 SkyActiv-D is an increasing oil level in the engine crankcase. This occurs due to:
- Multiple fuel injections required for particulate filter regeneration
- Fuel seeping past piston rings
- Fuel diluting the engine oil with diesel
This problem is more noticeable on vehicles used predominantly in urban settings, where the engine often does not reach optimal operating temperature. Excessive oil dilution can lead to:
- Reduced lubrication properties
- Accelerated wear of moving components
- Difficult starting in cold winter conditions
Frequent DPF regeneration cycles
Diesel particulate filters (DPF) require periodic regenerations to burn off accumulated particulates. On models equipped with the 1.5 SkyActiv-D, many owners report abnormally frequent regeneration cycles, which can result in:
- Increased fuel consumption (up to 1–2 L/100 km during regeneration)
- Reduced engine performance
- Risk of DPF clogging with predominantly urban use
To minimize this issue, it is recommended to take longer routes at steady speeds (over 80 km/h) at least once a week to allow full regeneration of the filter.
Inadequate sizing for a sporty driving style
With only 105 hp and relatively heavy vehicles, the 1.5 SkyActiv-D may be overstressed by drivers with a more dynamic driving style. Many owners report:
- The need to keep the engine at higher revs for acceptable performance
- Premature wear beyond 200,000–250,000 km with aggressive driving
- Turbo issues at higher mileages
Estimated durability
While no official data exist, owner experience suggests the 1.5 SkyActiv-D can reach:
- 250,000–300,000 km with proper maintenance and balanced use
- Under 200,000 km with predominantly urban use or aggressive driving
- Over 300,000 km under optimum conditions (long trips, meticulous maintenance)
Recommendations for owners
To maximize the durability of the 1.5 SkyActiv-D engine:
- Avoid exclusively urban trips — periodically undertake longer journeys to allow complete DPF regeneration
- Adhere to oil-change intervals — in urban conditions, consider shortening to 15,000 km
- Monitor oil level — check monthly and note if the level rises
- Let the engine warm up — avoid high revs when cold
- Use high-quality fuel — prefer premium stations to reduce deposits
- Periodically inspect the intake system — clean the EGR valve and the intake manifold at 80,000–100,000 km
In conclusion, the Mazda 1.5 SkyActiv-D engine represents an interesting technical solution for the small diesel engine segment, but it requires careful use and rigorous maintenance to deliver the expected reliability. It is particularly suited for drivers who cover medium to long distances, and less recommended for exclusive urban driving.
