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SKU: 15999-AM001 | UPC: 4957266653388
HKS 03-06 EVO / 08 EVO GSR/MR 75 degree Low Temperature Oil Cooler Thermostat
The HKS 15999-AM001 oil cooler thermostat opens at a low 75°C (167°F) to direct engine oil through the cooler for rapid temperature reduction during demanding conditions. Engineered for 2003-2006 Mitsubishi Lancer Evolution VIII/IX and 2008+ Evolution X GSR/MR models it maintains stable oil temperatures above freezing levels to avoid viscosity loss and ensure consistent lubrication. This direct-fit unit installs between the engine block and oil cooler line for immediate response and reliable cooling control.
Key Features
- 75°C Opening Point: Activates at lower temperature than stock for faster oil cooling without excessive drop in cold weather preserving oil film strength.
- Precision Valve Design: Smooth wax pellet mechanism responds quickly to temperature changes directing flow only when oil exceeds set point for balanced thermal management.
- Compact Aluminum Housing: Lightweight durable construction resists corrosion and withstands high-pressure oil flow in performance engines.
- Direct OEM Replacement: Matches factory mounting points on Evo 4G63 and 4B11 engines for bolt-on fit without modifications.
- Motorsport Tested: Proven in rally and circuit applications to hold oil temps steady under sustained high loads extending engine life.
Product Notes
- Pair with HKS oil cooler kit for full system efficiency.
- Inspect O-rings during install and replace if worn.
- Ships in protective packaging to prevent damage.
Installation Notes
- Professional installation recommended.
- Drain engine oil before removing stock sandwich plate.
- Uses existing M14x1.5 ports no additional hardware needed.
This Part Fits
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2003-2005 | Mitsubishi | Lancer Evolution | VIII |
| 2005 | Mitsubishi | Lancer Evolution | VIII MR |
| 2005-2006 | Mitsubishi | Lancer Evolution | IX |
| 2006 | Mitsubishi | Lancer Evolution | IX MR |
| 2008-2015 | Mitsubishi | Lancer Evolution | X GSR |
| 2008-2015 | Mitsubishi | Lancer Evolution | X MR |
Why Choose HKS?
- Decades of JDM tuning leadership with Super Taikyu endurance wins.
- Components built to Formula drift and rally standards for real-world reliability.
- Exact engineering tolerances ensure leak-free operation under boost.
Frequently Asked Questions
-
Q: Does this fit all 2003-2006 Evo models?
A: Yes it bolts directly to Evolution VIII and IX including MR variants using standard oil sandwich plate location on 4G63 engine. -
Q: What material is the thermostat body?
A: CNC-machined aluminum with stainless steel internals for heat resistance and long-term durability in high-heat oil circuits. -
Q: Is warranty coverage included?
A: HKS offers manufacturer defect warranty contact seller for claims processing after verifying proper installation.
Shipping & Handling
- Method: UPS Ground or USPS Priority
- Availability: In stock - ships same or next business day
- Packaging: Secure box dimensions 4.72 x 3.94 x 2.36 inches
- Weight: 4.8 ounces
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