What Causes Loud Engine Noise During Cold Start?

[ONolan]

Engine noise during cold start can be attributed to the following reasons: 1. The engine oil does not meet the standard or is overfilled, increasing the stirring resistance of the crankshaft connecting rod; 2. The oil viscosity is unsuitable; 3. Excessive engine carbon buildup, which aggravates wear on the cylinders and pistons; 4. Mixing different brands of engine oil; 5. Not changing the engine oil on time. Solutions to reduce loud engine noise during cold start include: 1. Refer to the maintenance manual or consider your driving environment and frequency to change the engine oil regularly; 2. Use the same brand or the same grade of engine oil; 3. Clean the three-way catalytic converter and throttle carbon buildup; 4. Use the gasoline grade recommended in the vehicle manual.