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My LS uses a quart every 500 to 1,000 miles — is it a PCV problem or worn rings?

Both are possible, and GM LS engines are known for using oil. Supercharged, turbocharged and high-rpm engines use even more (OnAllCylinders). Check in this order:

  1. Oil vapor through the PCV system: oil pulled into the intake condenses there, builds carbon on the valves and can foul the catalytic converter. An air/oil separator (catch can) in the PCV line and a low-volatility oil are the standard fixes.
  2. AFM (Displacement on Demand) engines: Speedway notes AFM engines tend to use more oil as they age (a quart between changes isn't uncommon), and burning oil (blue smoke) can signal a failing AFM system.
  3. Rings and valve seals: if the PCV fixes don't help, run a compression and leakdown test before blaming the rings.

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