FAA Aviation Mechanic Powerplant (AMP)Fuel, Induction and LubricationMedium
A mechanic is inspecting the oil dilution system on a reciprocating engine. What is the primary purpose of an oil dilution system?
- ATo filter contaminants from the engine oil during operation.
- BTo decrease oil viscosity for easier cold-weather starting.
- CTo maintain a constant oil pressure under varying engine loads.
- DTo increase oil viscosity for better lubrication at high temperatures.
Show answer & explanationAnswer & explanation
Correct answer: B. To decrease oil viscosity for easier cold-weather starting.
An oil dilution system is designed to inject a small amount of gasoline into the engine oil, typically before shutdown in cold weather. This temporarily decreases the oil's viscosity, making it thinner and allowing for easier engine cranking and starting in very cold conditions.
Why the other options are wrong
- A. Oil filters are responsible for filtering contaminants, not the oil dilution system.
- C. Oil pressure is maintained by the oil pump and pressure relief valve, not the dilution system.
- D. Oil dilution decreases viscosity, it does not increase it.
Oil Dilution System
A system that injects a small amount of gasoline into the engine oil to temporarily reduce its viscosity for easier cold-weather starting.
- Used in very cold climates.
- Gasoline evaporates out of the oil once the engine warms up.
- Improves cranking speed and reduces engine wear during cold starts.
Memory trick: Dilution is the 'gasoline shot' to thin cold oil, like thinning syrup.