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2016 Mazda6 2.5L Excessive Oil Consumption - No Visible Leaks

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Chris P. · rep 0 · May 22, 4:49 AM · 1 replies · solved · Question

Vehicle: 2016 Mazda6 Grand Touring

Hello everyone,

I own a 2016 Mazda6 Grand Touring with the 2.5L engine, and I've noticed a concerning trend: it seems to be consuming a lot of oil. I typically get my oil changed every 5,000 miles, but lately, I've had to add at least 1-2 quarts between changes just to keep it at a safe level. There are no visible leaks on my driveway or under the car, and I don't see any blue smoke from the exhaust.

I'm really puzzled because the car runs fine otherwise, no check engine light, no strange noises. It just seems to be burning through oil. Has anyone with a similar Mazda6 experienced this? Is this normal for these engines, or should I be worried?

Any advice on what could be causing this or what I should check would be greatly appreciated. Thanks!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:49 AM

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ClearTheCode admin answer:

Excessive oil consumption without visible leaks or smoke can be a frustrating issue, but it's not unheard of in some engines, including certain Mazda 2.5L units from that era. Here's what could be happening and what to investigate:

  1. PCV (Positive Crankcase Ventilation) Valve:

    • Function: The PCV system is designed to vent crankcase gases. A faulty or clogged PCV valve can lead to excessive vacuum in the crankcase, drawing oil vapor into the intake manifold where it's burned off.
    • Check/Replace: This is a relatively inexpensive part and a common cause of oil consumption. It's worth inspecting or replacing.

  2. Valve Stem Seals:

    • Function: These seals prevent oil from leaking down the valve stems into the combustion chambers. Over time, they can harden or wear out, especially on higher mileage engines.
    • Symptoms: Worn valve stem seals often cause a puff of blue smoke on startup after the car has been sitting for a while, though it might not always be noticeable.

  3. Piston Rings:

    • Function: Piston rings seal the combustion chamber and scrape oil off the cylinder walls. If they are worn, stuck, or damaged, oil can get past them and burn in the combustion chamber.
    • Diagnosis: This is a more serious and costly repair, often requiring an engine tear-down. A compression test and a leak-down test can help diagnose piston ring issues.

  4. Oil Viscosity:

    • Incorrect Oil: Ensure you are using the correct oil viscosity (e.g., 0W-20) as specified in your owner's manual. Using a thinner oil than recommended can sometimes exacerbate consumption.

  5. When to See a Shop:

    • If you've checked the PCV valve and confirmed correct oil usage without improvement.
    • If the oil consumption continues to increase.
    • A professional can perform a thorough diagnostic, including compression and leak-down tests, to accurately determine the source of the oil consumption. While some consumption is normal, 1-2 quarts every 5,000 miles is on the higher side and warrants investigation to prevent potential long-term engine damage.
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