A-Premium Engine Coolant Radiator Assembly with Integrated Transmission Oil Cooler — Direct Fit for GM SUVs, L6 4.2L, Core 18.13x2

A-Premium Engine Coolant Radiator Assembly with Integrated Transmission Oil Cooler is a direct-fit replacement designed to restore proper engine cooling and protect automatic transmissions on specific GM and related models.

This radiator assembly combines a high-efficiency core with a built-in transmission oil cooler to return overheating protection and stable operating temperatures to vehicles that match the listed fitments. Built to A-Premium's quality standards and backed by a one-year unlimited-mileage guarantee, it replaces the original radiator to help maintain factory-level cooling performance for engines and transmissions on compatible SUVs.

Which vehicles does this radiator fit and how do I confirm compatibility?

This assembly is engineered for a range of mid-2000s GM platform SUVs and related models. Confirm fitment by matching year, model, engine size (L6 4.2L where noted), and the automatic transmission requirement, and compare reference numbers if available.

• Compatible models: Buick Rainier (2004–2007), Chevrolet Trailblazer (2002–2009) and Trailblazer EXT (2002–2006)
• Also fits: GMC Envoy (2002–2009), Envoy XL (2002–2006), Envoy XUV (2004–2005)
• Other fits: Isuzu Ascender (2003–2008), Oldsmobile Bravada (2002–2004), Saab 9-7X (2005–2009) with L6 4.2L automatic
• Reference numbers to cross-check: 2458, CU2458, 8012458, 15179051, 15196385

What are the key dimensions and connection specs I should check?

Knowing the core dimensions and inlet/outlet sizes helps ensure the part matches the vehicle's mounting and hose connections. Measure your existing radiator or compare specification values to avoid installation issues.

• Core height: 18.13 inches; core width: 26.63 inches; core thickness: 1 inch
• Transmission oil cooler: integrated into the assembly for compact installation
• Inlet diameter: 1.31 inches; outlet diameter: 1.56 inches
• Designed as a direct-fit replacement—verify mounting locations and hose fittings on your vehicle

How does the integrated transmission oil cooler benefit my vehicle?

The built-in transmission oil cooler lowers automatic transmission fluid temperatures by routing fluid through dedicated passages inside the radiator. Cooler transmission fluid reduces wear and helps maintain shift quality under towing or heavy-load conditions.

• Combines engine coolant cooling and transmission fluid cooling in a single assembly
• Reduces the need for a separate external cooler and extra plumbing
• Helps stabilize operating temperatures during heavier use like towing or long highway drives
• Factory-style installation footprint simplifies replacement

What warranty and quality assurances come with this radiator?

A-Premium builds and tests this radiator assembly to meet strict performance standards and offers a one-year unlimited-mileage guarantee. The warranty covers manufacturing defects, giving added confidence when replacing a core cooling component.

• One-year unlimited-mileage guarantee from A-Premium
• Manufactured and tested to restore proper cooling performance
• Sold as a complete assembly to replace the OEM radiator and integrated cooler

Who is this for: This A-Premium radiator assembly is for owners or technicians working on compatible Buick, Chevrolet, GMC, Isuzu, Oldsmobile, and Saab SUVs from the 2002–2009 model years who need a direct-fit replacement that includes a transmission oil cooler. It’s intended for drivers who expect reliable, OEM-like cooling performance after radiator failure, who tow or carry heavier loads, or who simply want to replace a leaking, clogged, or damaged radiator with a tested aftermarket assembly that includes clear specifications for fitment and connections.