How long can you leave an engine sitting?

How Long Can You Leave an Engine Sitting?

Modern vehicles are designed to be driven regularly. When a car sits for extended periods, various components can deteriorate, leading to mechanical issues. The engine, in particular, is vulnerable to damage if left unused for too long.

Short-Term Effects (Up to Two Weeks)

If a car is left unused for up to two weeks, there are minimal risks to the engine. However, certain issues can arise if the vehicle is not properly prepared for storage. For instance, stale fuel can gum up the fuel system, while battery discharge can prevent the engine from starting.

Extended Periods (Two Weeks to Six Months)

Leaving an engine sitting for extended periods, between two weeks to six months, can lead to more significant problems. The following issues can occur:

• Oil Settling: Oil drains from the engine components and collects in the oil pan. This can leave critical engine parts unprotected and prone to wear.
• Moisture Accumulation: Moisture can condense inside the engine, leading to corrosion. This is especially prevalent in humid environments.
• Fuel Degradation: Fuel can oxidize and become less flammable over time. This can make starting the engine difficult and can damage the fuel system.
• Battery Discharge: Batteries discharge slowly over time, especially if the car is not connected to a battery charger. A discharged battery can prevent the engine from starting.

Long-Term Effects (Over Six Months)

Leaving an engine sitting for more than six months without use can cause severe and potentially irreversible damage. The following issues can occur:

• Oil Thickening: Oil can thicken and become sludge-like, blocking oil passages and impairing lubrication.
• Cylinder Rust: Moisture can cause the cylinder walls to rust, damaging the engine’s compression and performance.
• Valve Damage: Valves can stick or seize in their guides, preventing proper engine operation.
• Fuel System Failure: Fuel injectors and other fuel system components can become clogged or damaged from sitting with stale fuel.

Prevention

To prevent engine damage from extended storage, it is crucial to take precautionary measures:

• Prepare the Vehicle: Fill the fuel tank, add fuel stabilizer, and change the oil. Disconnect the battery or connect it to a battery charger.
• Start the Engine Regularly: Start the engine every few weeks and run it for a short period. This circulates oil, prevents fuel degradation, and recharges the battery.
• Consider Fogging: Spraying a fogging oil into the engine through the air intake can protect the cylinder walls from rust.
• Store in a Dry, Ventilated Location: Choose a storage location that is dry and well-ventilated to prevent moisture accumulation.

Regular operation of a vehicle is the best way to prevent engine damage. If extended storage is unavoidable, follow these guidelines to minimize the risks.