What causes this on a Toyota Corolla: ZZ oil consumption (1ZZ-FE/3ZZ-FE, worse on early builds)?

Piston oil-control rings and oil-return holes clog or stick. Toyota revised the rings around 2005. Worn valve stem seals at high km.

Measure consumption (above ~1 L/1,000 km is excessive). Fix with new rings and pistons (updated), valve stem seals or a short block.

ZZ oil consumption (1ZZ-FE/3ZZ-FE, worse on early builds)

Symptoms: Oil level drops between changes, blue smoke, oil-fouled plugs and misfire
Likely cause: Piston oil-control rings and oil-return holes clog or stick. Toyota revised the rings around 2005. Worn valve stem seals at high km.
Fix: Measure consumption (above ~1 L/1,000 km is excessive). Fix with new rings and pistons (updated), valve stem seals or a short block.
Applies to: ZZE121R, ZZE122R (PK); JDM ZZE12#
Related fault codes: P0300-P0304 (secondary)
Confidence: medium