Piston Rings
WARNING: This page is about a different car, the 2001 Mazda MPV and 2000 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.
Check piston ring end clearance and side clearance. See PISTONS, PINS & RINGS under ENGINE SPECIFICATIONS. If not within specification, replace piston rings, or rebore engine block and install new pistons and rings.