SHY6

Mazda 2.2 SKYACTIV-D (SHY6) 150 HP – Experiences, issues, fuel consumption and used car buying tips

Key points (TL;DR):

• The SHY6 engine is a powerful and refined bi-turbo diesel, but it requires strict and preventive maintenance.
• Injector washers are a critical point – if they fail, soot enters the oil pan, clogs the oil pump strainer and leads to total engine failure.
• The engine does not have an issue with oil consumption, but with rising oil level due to diesel fuel dilution during frequent DPF regenerations in city driving.
• The timing chain drive is more durable than on the first generation, but it still has to be checked around 150,000 km.
• 380 Nm of torque makes this engine extremely flexible and pleasant to drive, so the weight of the CX-5 is barely noticeable.
• This is not an engine for exclusively city driving – the EGR and DPF will clog quickly, which leads to expensive repairs.

Contents:

• Introduction: Engine overview
• Technical specifications
• Reliability and maintenance
• Specific parts and costs
• Fuel consumption and performance
• Additional options and modifications
• Gearbox and drivetrain
• Buying used and conclusion

Introduction: Engine overview

When Mazda introduced its SKYACTIV-D technology, the automotive world was intrigued. The SHY6 engine with 2191 cc and 110 kW (150 HP), installed in the second generation CX-5 (including the 2021 facelift), is known for its exceptionally low compression ratio for a diesel engine (14:1). This engineering decision brought smoother operation, lower NOx emissions and better performance, but also introduced some specific weaknesses. This engine is the heart of Mazda’s SUV lineup and offers an excellent compromise between the base engine and the more expensive 184 HP version.

Technical specifications

Reliability and maintenance

The SHY6 engine uses a timing chain instead of a belt. Although early SKYACTIV-D engines (before 2016) had major issues with chain stretching and camshaft damage, in the second-generation CX-5 and SHY6 engines the materials were significantly improved. However, chain stretch has not been eliminated 100%. A major service, i.e. replacement of the chain, guides and tensioner, is usually done when diagnostics show a mismatch between camshaft and crankshaft angles, or when rattling appears on a cold start – most often between 150,000 and 200,000 km. The cost of this job is high (depends on the market).

The most common and most dangerous failure on this engine is related to the injector washers. These copper washers burn out over time. When that happens, hot gases from the combustion chamber pass by the injector straight under the valve cover and burn the engine oil. This creates thick soot that falls into the oil pan and clogs the oil pump strainer. Symptom: the oil pressure warning light comes on. If you don’t switch the engine off immediately, it loses lubrication and the crankshaft can break or the engine can seize. That’s why it is strongly recommended to replace the injector washers preventively every 60,000 to 80,000 km. The cost of replacing the washers is low, but it saves an engine worth several thousand euros.

As for oil, the engine takes 5.1 liters with the filter. Only 0W-30 or 5W-30 with ACEA C3 approval (Mazda Original Oil Supra DLT) is recommended. Interestingly, this engine rarely consumes oil in the sense of the level dropping on the dipstick. On the contrary, the oil level often rises! Why? If the car is driven on short trips in the city, the DPF constantly attempts regeneration by injecting extra fuel. That unburnt diesel runs down the cylinder walls into the oil pan and dilutes the oil. On the dipstick, above the maximum mark, there is an “X” mark. If the oil level reaches “X”, the oil must be changed immediately because it has lost its lubricating properties.

Injectors (Denso) are quite durable, but very sensitive to poor-quality fuel. Their lifespan in optimal conditions is around 200,000 to 250,000 km. If the injectors start to “dribble” (do not atomize fuel properly), you will see black smoke, rougher idle, and over time this can lead to piston damage.

Specific parts (costs)

This model is equipped with advanced systems in order to deliver performance and meet strict emission standards.

• Turbochargers: The SHY6 uses two turbochargers (bi-turbo system) – a smaller one for low revs and a larger one for high revs. Because of this, the engine has virtually no “turbo lag” and pulls linearly. Their lifespan is excellent provided the oil is changed on time (every 10,000–15,000 km at most). If a turbo fails, overhaul or replacement is very expensive (depends on the market) due to the complexity of the system.
• Injection system: The Denso system is reliable, but overhauling these injectors is often impossible or not cost-effective, so in case of failure you usually have to buy new or tested used ones.
• DPF and EGR: The engine has a DPF filter and both low- and high-temperature EGR valves. Due to the massive flow of recirculated gases, the intake manifold and EGR valves get extremely dirty very quickly (carbon deposits). Cleaning the intake manifold (decarbonization) is a mandatory part of maintenance every 80,000–100,000 km. The DPF clogs if the car is driven mostly in the city.
• AdBlue (SCR): In newer models and variants after 2018 (especially the 2021 facelift for Euro 6d standards), this engine is equipped with an AdBlue system. Although more reliable than those of some French rivals, failures still occur on the tank heater or the pump. Fixing these issues is expensive (depends on the market).

Fuel consumption and performance

With an impressive 380 Nm of torque available from just 1800 rpm, this engine is absolutely not sluggish, even in the heavy CX-5 body, and even when paired with AWD (4x4). Throttle response is excellent thanks to the small turbocharger.

Real-world fuel consumption:

• City driving: Expect between 7.5 and 9.0 l/100 km. If the vehicle has AWD and an automatic gearbox, in winter conditions and heavy traffic, consumption can exceed 9 liters.
• Motorway: This is the natural environment for the SHY6. At 130 km/h the engine cruises at a very relaxed ~2300 rpm (depending on the gearbox). Motorway consumption is around 6.5–7.0 l/100 km.

Additional options and modifications

Since mechanically (hardware-wise) this 150 HP engine is almost identical to the more powerful version (175 or 184 HP depending on model year), the SHY6 is very suitable for remapping (Stage 1). Without any risk to the components, power can be raised via software to about 185–190 HP, and torque goes beyond 430 Nm. After this, the engine breathes much easier, overtakes are safer, and many drivers even report a slight drop in fuel consumption on the open road. However, only do this with reputable tuners who use a dyno.

Gearbox

Two options are available with this engine: a 6-speed manual (SKYACTIV-MT) and a 6-speed automatic (SKYACTIV-Drive).

Automatic gearbox (Editor’s recommendation)

The automatic gearbox is a classic torque converter unit, not a dual-clutch. It is extremely reliable, smooth and durable. Failures are very rare, under one condition: the automatic transmission fluid must be changed every 60,000–80,000 km (either by drain-and-fill or machine flushing). Mazda does not prescribe mandatory replacement, claiming it is “sealed for life”, but real-world experience from mechanics shows that changing the fluid is essential for longevity.

Manual gearbox

The manual gearbox has short, precise throws and is excellent to drive. However, models with a manual gearbox have a dual-mass flywheel. Given the high torque of 380 Nm, the dual-mass flywheel is subjected to heavy loads, especially during hard acceleration from low revs. A clutch kit with dual-mass flywheel usually lasts around 150,000–180,000 km. The replacement cost (parts + labor) is very high (depends on the market). The oil in the manual gearbox should be changed at around 100,000 km.

Buying used and conclusion

When buying a Mazda CX-5 with this engine, a visual inspection doesn’t tell you much. Here is what you absolutely must check:

• Pull out the dipstick: Check the oil level. If it’s in the middle – great. If it’s close to the “X” mark at the very top, the engine has an issue with frequent interrupted DPF regenerations. Smell the oil; if it strongly smells of diesel, be cautious.
• Diagnostics are mandatory: Connect the car to Mazda-specific diagnostics. Check DPF saturation (PM accumulation values), oil pressure and parameters that indicate chain stretch.
• Washer replacement history: Check whether the injector washers have been replaced. If the owner has no idea what you’re talking about – walk away from that car or plan for that expense on day one after purchase, along with removing the oil pan and cleaning the oil pump strainer.
• Cold start: Listen to the engine when it is completely cold. Rattling from the timing side indicates a worn chain.

Conclusion: Who is this engine for?
The Mazda 2.2 SKYACTIV-D (SHY6) is a fantastic engine for people who cover high annual mileage on open roads and motorways. That is where it shows its flexibility, quiet operation and efficiency. However, if you use your car to take kids to school, commute three kilometers through city traffic and go to the supermarket – do not buy this diesel. Constant city driving will choke the engine, cause problems with the oil, DPF and intake manifold, and turn maintenance into a nightmare.