MAHLE 42120CP.030 Plasma-Moly Piston Ring Set GM Oversize - 3.5L 3.9L V6 030

The MAHLE 42120CP.030 is a premium plasma-moly piston ring set engineered for GM 3.5L and 3.9L V6 engines (engine codes L24, LZE, LGD, and L29) at a +0.030" oversize bore diameter. Designed to meet or exceed original equipment specifications, this ring set delivers reliable sealing, reduced oil consumption, and long service life for engine rebuilds and overhauls.

Key Features:

• Plasma-moly top ring coating on a carbon steel upper compression ring (UCR) for superior wear resistance and break-in characteristics
• Pre-lapped design seats immediately upon installation, virtually eliminating traditional break-in time
• Barrel-faced compression ring contact area with CNC-controlled gap chamfer for optimized compression and reduced blow-by
• Intermediate/lower compression ring (LCR) features a reverse twist design for enhanced groove side sealing and taper-race machining for improved contact
• CP-20 oil ring assembly with a 20-degree ear angle for best-in-class side sealing against the cylinder wall, plus a chemically polished expander for superior oil drain-back
• Ring tension and materials optimized per application for reduced friction and extended engine life
• Meets OE specifications for compression, oil control, and dimensional accuracy
• Sold as a complete set for one engine (6 cylinders)

Ring construction uses carbon steel for both the upper and lower compression rings and stainless steel for the oil control ring, with axial heights of 1.5mm (UCR), 1.5mm (LCR), and 4.0mm (OCR). Ring types are UCR: RF-13PF, LCR: THM-13, and OCR: CP-20 Shallow Groove.

MAHLE is a global leader in piston ring technology, combining decades of OE development experience with advanced manufacturing to produce rings trusted by professional engine builders worldwide.