Life time Warranty
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  • Direct fit for 2003-2007 Dodge Ram 5.9L Cummins
  • Equivalent to OEM specifications for fit and function
  • Replaces leaking or failing factory transmission oil cooler
  • Durable, corrosion-resistant aluminum construction
  • Includes bracket for easy installation
  • Utilizes all factory lines and hardware
  • No modification required for installation
  • Includes Mishimoto Lifetime Warranty


The factory transmission oil cooler on your 2003-2007 Dodge Ram 5.9L Cummins is a liquid-to-liquid cooling unit, utilizing the engine’s cooling system to cool the transmission fluid during warm outside temperatures and warm the fluid during cold outside temperatures. This design is tried and true, and it works. Until it doesn’t. When they wear out and fail, it can leak coolant into your transmission fluid. Mixing coolant into your transmission fluid can have catastrophic results, and nobody wants to spend thousands of dollars to rebuild or replace their transmission if it can be avoided. The Mishimoto Replacement Transmission Oil Cooler is a direct fit, OEM replacement that requires no modification to install. Made to OEM specifications, this transmission oil cooler is equivalent to an OEM part. By replacing your transmission cooler preventatively, you can save your transmission from falling victim to premature failure. As with all of our products, this cooler is backed by our signature Mishimoto Lifetime Warranty.

Mishimoto Automotive (“Mishimoto”) warrants its products under this lifetime limited warranty policy (“Warranty Policy”). This Warranty Policy applies solely to: (i) Mishimoto Products purchased directly from Mishimoto or Mishimoto authorized dealers (each a “Mishimoto Product” and collectively, the “Mishimoto Products”) and (ii) the original purchaser of such Mishimoto Product (“Purchaser”). This Warranty Policy is non-transferable and all claims under this Warranty Policy must be accompanied by the original sales receipt. The terms and conditions of this Warranty Policy are subject to change by Mishimoto at any time without notice.

For our complete warranty policy, please click here.