4721801712 Genuine Detroit Diesel® Oil Coolant Module For DD15

1. Prevents oil overheating

Under heavy load (like hauling or highway driving), oil gets very hot.
The module removes excess heat using engine coolant.

2. Speeds up warm-up

When the engine is cold:

• Coolant warms up faster than oil
• The module transfers heat to the oil
  

3. Maintains proper lubrication

Stable oil temperature means:

• Better lubrication of engine parts
• Less wear on bearings, pistons, and turbo components

4. Improves engine durability

By keeping oil in its ideal range, it helps:

• Extend engine life
• Prevent internal damage

5. Supports emissions and efficiency

Modern engines (like those in Volvo Trucks and Freightliner) rely on precise temperatures for:

• Fuel efficiency
• Emissions control systems

1. Oil mixed with coolant

• Coolant looks milky / chocolate-colored
• Oily film in the radiator or overflow tank

2. Coolant mixed with oil

• Engine oil looks milky or foamy
• Oil level may rise unexpectedly

3. Engine overheating

• Oil isn’t being cooled properly
• Temperature gauge runs higher than normal

4. Oil temperature too high

• Especially under load (towing, highway, hills)

5. Low oil pressure

• Thinned-out or overheated oil loses pressure
• Warning light may come on

6. Poor engine performance

• Increased wear, rough operation over time

7. Oil or coolant leaks

• Around the oil cooler/module housing
• Drips under the truck