Performance Radiator for Buick Rainier (2004-2007) 4.2L Automatic

High-Efficiency 3-Row Aluminum Performance Radiator for 2004-2007 Buick Rainier

Direct drop-in cooling upgrade: Replaces failure-prone OEM plastic-tank units with an all-aluminum 3-row core to maximize heat rejection under heavy load and prevent thermal runaway in the 4.2L Atlas inline-six.

The Stock Rainier Thermal Vulnerability

Factory GMT360 cooling assemblies rely on single-row aluminum cores crimped to molded plastic end tanks. Over repeated thermal cycles, the factory rubber gasket degrades, while continuous engine bay heat causes the polymer tanks to embrittle and crack along the crimp seam. Under sustained load or stop-and-go driving, the narrow stock core quickly succumbs to heat soak, driving up coolant temperatures and putting the Atlas LL8 cylinder head at risk of warping.

The Engineering Solution

This heavy-duty unit features a 100% TIG-welded aircraft-grade aluminum construction, eliminating crimped plastic tanks entirely. The 3-row core design expands internal fluid capacity and surface area, dramatically improving convection efficiency across the 18.1" x 26.75" core matrix. Engineered with an integrated M14x1.5 transmission oil cooler, it ensures optimal ATF operating temperatures to protect the 4L60-E automatic gearbox from fluid degradation during towing.

Technical Specifications

Compatibility

• 2004 Buick Rainier CXL / CXL Plus 4.2L L6 Automatic
• 2005 Buick Rainier CXL 4.2L L6 Automatic
• 2006 Buick Rainier CXL 4.2L L6 Automatic
• 2007 Buick Rainier CXL 4.2L L6 Automatic
• Note: Fits 4.2L I6 models only; does not fit 5.3L V8 configurations.

The Buick Durability Standard

Engineered to handle elevated thermal demands when hauling or traversing steep inclines, this all-aluminum core ensures strict cooling stability and extended transmission lifespan without fluid cross-contamination risks.