Why is the engine noise louder after changing the oil in a new car?
3 Answers
There are 6 main reasons why the engine noise becomes noticeably louder after an oil change: 1. The oil doesn't meet specifications or too much was added. 2. The oil viscosity needs to be appropriate. 3. Carbon buildup exists. 4. Mixing different brands of oil. 5. Not changing oil on schedule. 6. Psychological effect. More detailed reasons for increased engine noise after oil change are as follows: (1) Overfilling oil - Actually, louder engine sound after oil change is common, possibly due to overfilling. This increases resistance to crankshaft rotation, reduces engine power, alters air-fuel ratio in combustion chamber, and raises knock probability, thus increasing noise. (2) Inappropriate oil viscosity - When new oil is added, the engine may need time to adapt to the oil's viscosity, potentially revving higher and causing louder noise. This usually normalizes after a break-in period. (3) Additionally, the oil viscosity might be unsuitable. If too low, lubrication becomes insufficient, causing part wear and abnormal sounds. If too high, it overloads the engine, also generating noise.
Last week I encountered the same issue - the engine suddenly became noticeably noisier with a distinct buzzing sound after an oil change. My first thought was incorrect oil viscosity, as different engines have specific viscosity requirements. The owner's manual clearly states the recommended grade, such as 0W-20 or 5W-30. During my last service, I used 5W-40 oil which offers better high-temperature protection but has poorer flow characteristics, resulting in louder cold-start noises. Also pay attention to the oil level - a friend's car had half a liter overfill due to the mechanic's error, exceeding the dipstick's maximum mark. This caused increased foaming and reduced lubrication effectiveness. Another possibility could be improper oil filter installation leading to pressure loss - listen for hissing sounds near the intake pipe at idle. I recommend first checking the oil level and grade yourself, and if the issue persists, return to the workshop for inspection.
Just after an oil change, the noise is loud. I usually start by ruling out basic issues. Check the dipstick to see if there's too much oil—if the oil level exceeds the MAX line, it can create bubbles and affect lubrication. Also, confirm the oil grade; in sub-zero temperatures, higher viscosity oil makes cold starts more strenuous. The mechanic last time reminded me: it takes about 200 kilometers for the new oil film to form, so slightly louder noise during the first few ignitions is normal. However, if accompanied by sluggish throttle response or metallic grinding sounds, it might be due to inferior oil or a clogged oil filter. Metallic grinding sounds are particularly dangerous, indicating possible insufficient lubrication and wear on the bearing shells. Try gently pressing the accelerator to locate the sound source—high-pitched squeals and low-pitched rumbles point to entirely different issues. The safest approach is still to return to the shop and use a diagnostic tool to read the engine's data stream.
