Description

HKS Low Temp Oil Cooler Thermostat for Mitsubishi Evo I–X — Part #15999-AM001

Firstly, Buy HKS Low Temp Oil Cooler Thermostat 15999-AM001 for Mitsubishi Evo I-X. 75°C oil thermostat for improved oil cooling. The HKS Low Temp Oil Cooler Thermostat 15999-AM001 is a performance-focused replacement thermostat designed for Mitsubishi Lancer Evolution oil cooling systems. Developed by HKS, this low-temperature oil thermostat opens at 75°C (167°F), compared with approximately 100°C (212°F) for the factory oil thermostat. By opening the oil circuit at a lower temperature, the HKS thermostat allows engine oil to reach the oil cooler sooner, making it a useful upgrade for Evo owners who regularly drive in demanding conditions.

The HKS 15999-AM001 is listed for Mitsubishi Lancer Evolution models from Evolution I through Evolution X, covering both the 4G63 and 4B11 engine platforms depending on the generation. HKS specifically lists applications including Evo I–IX with the 4G63 and Evo X with the 4B11.

HKS Low Temp Oil Cooler Thermostat 15999-AM001

Engine oil performs several important functions in a high-performance turbocharged engine. In addition to lubricating internal components, engine oil helps carry heat away from areas exposed to high temperatures. During sustained hard driving, track use, hot-weather operation, or modified-engine applications, controlling oil temperature becomes increasingly important.

The HKS Low Temp Oil Cooler Thermostat is designed to control when engine oil is routed through the oil cooler. Its 75°C opening temperature provides an earlier transition to oil cooling compared with the stock thermostat specification cited by HKS.

This makes the 15999-AM001 a practical component for Evo owners upgrading or maintaining their oil cooling system. It can be used as a replacement for the stock oil thermostat on compatible Lancer Evolution applications, while also being incorporated into HKS oil cooler systems.

75°C Low-Temperature Oil Thermostat

The defining feature of the HKS 15999-AM001 is its 75°C opening temperature. HKS states that its Lowtemp Thermostat opens at 75°C, while the stock oil thermostat opens at 100°C.

Opening the oil-cooling circuit at a lower temperature can allow the oil cooler to begin managing oil temperature sooner. This can be particularly relevant for vehicles subjected to repeated acceleration, high engine load, track driving, or warm ambient temperatures.

It is important to remember that an oil thermostat does not simply make the engine oil “cold.” Instead, it controls oil flow through the cooler according to the thermostat’s operating temperature. The objective is to manage oil temperature while maintaining proper lubrication conditions.

Mitsubishi Evo I–X Applications

HKS provides extensive application information for part number 15999-AM001. The listed Mitsubishi applications include:

• Evo I — CD9A — 4G63
• Evo II — CE9A — 4G63
• Evo III — CE9A — 4G63
• Evo IV — CN9A — 4G63
• Evo V — CP9A — 4G63
• Evo VI — CP9A — 4G63
• Evo VII — CT9A — 4G63
• Evo VIII — CT9A — 4G63
• Evo VIII MR — CT9A — 4G63
• Evo IX — CT9A — 4G63
• Evo IX MR — CT9A — 4G63
• Evo X — CZ4A — 4B11

HKS’s official application chart also lists the Evo Wagon CT9W with the 4G93 engine for this part number.

Buy HKS Low Temp Oil Cooler Thermostat 15999-AM001 for Mitsubishi Evo I-X. 75°C oil thermostat for improved oil cooling, Shop online at Evomotorparts.

Always verify your exact chassis, engine, oil cooler configuration, and model year before ordering because oil-cooling hardware can differ between applications.

Features and Benefits

The HKS Low Temp Oil Cooler Thermostat 15999-AM001 offers several useful features for Mitsubishi Evolution builds:

• HKS performance-engineered component
• 75°C (167°F) valve opening temperature
• Lower opening temperature than the stock 100°C oil thermostat
• Designed as a replacement for the stock oil thermostat on compatible Evo models
• Compatible with HKS oil cooler systems
• Suitable for Evo I through Evo X applications listed by HKS
• Supports both 4G63 and 4B11 Evo applications
• Useful for street, high-performance, and track-oriented builds
• Helps the oil cooler begin operating at a lower temperature

Firstly, the lower opening temperature allows the oil cooling circuit to engage earlier. Secondly, the component provides an OEM-replacement-style solution for compatible Mitsubishi Evolution applications. Thirdly, it can complement an upgraded oil cooler system where improved temperature management is required.

HKS also identifies the 15999-AM001 as a component used with its Oil Cooler Kit R Type, where the low-temperature thermostat is built into the thermo adapter assembly.

Oil Cooling for 4G63 and 4B11 Engines

The Mitsubishi Evolution platform has used several generations of turbocharged engines, with the legendary 4G63 powering Evo I through IX and the 4B11 powering the Evo X.

Both engines can generate substantial heat during high-load operation. For modified Evo vehicles producing increased power or vehicles regularly used for motorsport, oil temperature management is an important part of the overall engine cooling strategy.

HKS has specifically documented the use of the 15999-AM001 with Evo oil cooler systems. For example, HKS’s Evo IX oil cooler information identifies the low-temperature thermostat as a component that can improve the oil-cooling setup.

The thermostat can therefore be particularly relevant when upgrading an oil cooler, replacing an aging factory thermostat, or refreshing the lubrication system during a performance build.

Product Specifications

Brand: HKS
Product: Low Temp Oil Cooler Thermostat
Part Number: 15999-AM001
Opening Temperature: 75°C / 167°F
Stock Oil Thermostat Reference: 100°C / 212°F
Application: Mitsubishi Lancer Evolution I–X
Engine Platforms: 4G63 and 4B11 applications
Function: Controls oil flow through the oil cooler
Product Type: Low-temperature oil thermostat
Category: Engine Oil Cooling → Oil Cooler Thermostats

HKS’s own product documentation confirms the 75°C opening temperature and lists 15999-AM001 as a replacement for the stock oil thermostat on Lancer Evolution I through X.

Why Choose an HKS Low Temperature Oil Thermostat?

The HKS thermostat is designed specifically around performance oil-cooling requirements rather than being a generic coolant thermostat. Its lower opening temperature makes it suitable for enthusiasts who want the oil cooler circuit to begin operating sooner.

This can be useful for Evo owners in hot climates or those who frequently drive their cars aggressively. It can also be a sensible addition when installing an aftermarket oil cooler, provided the thermostat and adapter configuration are compatible with the vehicle.

The component is especially relevant to owners of classic and modern Evolution models looking for proven aftermarket performance parts from an established Japanese manufacturer.

Buy HKS 15999-AM001 Online

If you are looking for the HKS Low Temp Oil Cooler Thermostat 15999-AM001 for sale, verify your Evo’s model, chassis code, engine, and existing oil cooler configuration before ordering. The part is listed by HKS for Evolution I–X applications, making it a versatile oil-cooling component across multiple generations.

Whether you are maintaining an Evo IV 4G63, upgrading an Evo VIII or IX oil-cooling system, or building an Evo X 4B11 performance setup, the correct oil thermostat can be an important part of your overall temperature-management strategy.

At evomotorparts.com, you can shop online for HKS performance products and Mitsubishi Evo parts for street cars, track builds, restorations, and high-performance projects.

Frequently Asked Questions

What is the HKS 15999-AM001?

The HKS 15999-AM001 is a low-temperature oil cooler thermostat designed for compatible Mitsubishi Lancer Evolution applications. It controls oil flow through the oil cooler and opens at 75°C (167°F).

What temperature does the HKS 15999-AM001 open?

The HKS Low Temp Thermostat opens at 75°C (167°F). HKS lists the stock oil thermostat opening temperature as 100°C (212°F).

Does 15999-AM001 fit Evo 8 and Evo 9?

Yes. HKS lists the 15999-AM001 for the Evo VIII, Evo VIII MR, Evo IX, and Evo IX MR, all using the 4G63 platform.

Does it fit the Evo X?

Yes. HKS lists the 15999-AM001 for the Mitsubishi Lancer Evolution X, chassis CZ4A, with the 4B11 engine.

Can the HKS thermostat replace the factory oil thermostat?

HKS states that the Lowtemp Thermostat can replace the stock oil thermostat on Lancer Evolution I through X applications.

Is this thermostat for engine coolant?

No. The 15999-AM001 is an oil cooler thermostat, not the engine coolant thermostat. It controls engine oil flow through the oil cooler.

Is this suitable for a performance Evo build?

The HKS Low Temp Oil Cooler Thermostat is designed for performance oil-cooling applications and is particularly relevant when upgrading or maintaining an oil cooler system. Vehicle-specific compatibility should be confirmed before installation.

What does the lower opening temperature do?

The 75°C opening temperature allows the oil-cooling circuit to begin operating earlier than the stock 100°C thermostat specification cited by HKS. This can help manage oil temperature during demanding operation. Keep your Mitsubishi Evolution’s oil temperature management system properly equipped with the HKS Low Temp Oil Cooler Thermostat 15999-AM001, and shop evomotorparts.com for quality Mitsubishi Evo parts and performance components for your next build, maintenance project, or track setup.

Buy HKS Low Temp Oil Cooler Thermostat 15999-AM001 for Mitsubishi Evo I-X. 75°C oil thermostat for improved oil cooling, Shop online at Evomotorparts.