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Excessive Oil Consumption on 2017 Mazda6 Skyactiv-G

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Mike T. · rep 0 · May 25, 3:37 AM · 1 replies · solved · Question

Vehicle: 2017 Mazda6 Grand Touring

Hi everyone,

I'm a bit concerned about my 2017 Mazda6 Grand Touring with the 2.5L Skyactiv-G engine. It's got about 70,000 miles on it, and I've noticed it's consuming a significant amount of oil between changes. I'm having to add about a quart every 2,000-3,000 miles, which seems excessive for a modern engine.

There are no visible leaks, no blue smoke from the exhaust, and no 'Check Engine' light. The car runs fine otherwise. I'm using the recommended 0W-20 synthetic oil. I've read some forums mentioning this could be a known issue for some Skyactiv engines.

Is this normal for these engines, or should I be worried about something more serious like piston rings? What steps should I take to diagnose this?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:37 AM

0

ClearTheCode admin answer:

Excessive oil consumption in a 2017 Mazda6 2.5L Skyactiv-G engine, even without visible leaks or smoke, can be a concern. While some oil consumption is normal for any engine, adding a quart every 2,000-3,000 miles is on the higher side for a relatively modern engine like the Skyactiv-G.

Common Causes & Steps:

  1. PCV Valve System: A clogged or malfunctioning Positive Crankcase Ventilation (PCV) valve can lead to increased crankcase pressure, forcing oil past seals or piston rings. This is a relatively inexpensive part to replace and a good starting point for diagnosis.
  2. Valve Stem Seals: Over time, valve stem seals can harden and lose their elasticity, allowing oil to seep into the combustion chamber. This often results in a puff of blue smoke on startup or during deceleration, though it might not always be obvious.
  3. Piston Rings: Worn or stuck piston rings are a more serious cause. They can fail to properly scrape oil from the cylinder walls, leading to it being burned during combustion. This is usually diagnosed with a compression test and a leak-down test.
  4. Turbocharger Issues (if applicable): If your Mazda6 has the optional turbocharger, a failing turbo can also consume oil. However, the 2017 Mazda6 Grand Touring typically has the naturally aspirated 2.5L engine, so this is less likely unless it's a specific variant.
  5. Oil Viscosity: While you're using the recommended 0W-20, ensure it's a high-quality synthetic. Sometimes, switching to a different brand or a slightly thicker oil (if approved by Mazda for your climate/driving conditions) can marginally reduce consumption, but it's not a fix for an underlying problem.

When to See a Shop:

  • You should consult your Mazda dealership or a trusted independent mechanic. They can perform an oil consumption test, which involves precisely measuring the oil level, sealing the oil cap, and having you return after a set mileage (e.g., 1,000 miles) to re-measure. This helps quantify the consumption rate.
  • They can also perform a compression test and leak-down test to assess the health of your piston rings and valves.
  • There are no specific OBD-II codes for oil consumption itself, as it's a mechanical issue. However, if the consumption is severe enough to cause catalytic converter damage, you might eventually see codes like P0420 (Catalyst System Efficiency Below Threshold).
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