There are four main reasons why a car may make more noise after an oil change: 1. Incorrect oil quantity. When changing the oil, there is a specified standard. If too much oil is added, the crankshaft will have to work harder to rotate, requiring more power to push it, resulting in sluggish acceleration. Additionally, excessive oil may leak into the combustion chamber, leading to rapid oil consumption and engine carbon buildup, which can damage the engine. 2. Oil and engine mismatch. Different engines require different oils, as clearly stated in the car manual. If you previously used 20-weight oil but switched to 30-weight oil based on someone else's advice and experience sluggish acceleration, it could be a compatibility issue. Higher viscosity makes it harder for the crankshaft to rotate, and even if not overfilled, it can still cause significant issues. Conversely, oil that is too thin may not suit the engine, leading to noise. 3. Clogged oil filter or severe carbon buildup. When changing the oil, the oil filter should usually be replaced as well. However, some owners change the oil frequently or forget to replace the filter, leaving the old one in place. While this may not cause major problems immediately, if the filter becomes clogged and isn't replaced in time, oil will bypass through the relief valve, resulting in reduced power and increased engine wear. 4. Poor oil quality. When purchasing oil, owners must be vigilant, as the oil market is currently chaotic. Some discarded oil is simply reprocessed and repackaged as new oil for sale, unlike properly recycled oil, and it largely loses its effectiveness.
