What Causes Increased Engine Noise After an Oil Change?
4 Answers
There are several reasons why engine noise may increase after an oil change: 1. Overfilling of engine oil: When there is too much oil in the engine, it creates unnecessary resistance to the rotation of the crankshaft, affecting power output, increasing fuel consumption, and consequently raising noise levels. 2. Unsuitable oil viscosity: If the oil viscosity is too high, it creates greater rotational resistance when the engine is cold, leading to insufficient lubrication and resulting in louder noise during cold starts. 3. Severe engine carbon buildup: Over time, engine oil becomes thinner and carbon deposits accumulate. When new oil is first replaced, the engine may not immediately adapt to the new oil's viscosity, causing temporarily increased engine noise.
Last time my friend's car also had louder engine noise after an oil change, and I helped him troubleshoot it. The most common issues are either overfilling or underfilling the oil—you must carefully check the oil level using the dipstick. Another possibility is using the wrong oil viscosity; for example, a new car requiring 0W-20 but mistakenly using 5W-40, where the higher viscosity makes it hard for the oil pump to circulate, resulting in a knocking sound. Low-quality oil filters can also cause problems—if the filter paper clogs or the check valve leaks, it leads to insufficient oil supply, causing the valve lifters to grind dry and produce loud noise. If this is accompanied by reduced power, it might be because the old oil was drained too thoroughly, and accumulated sludge has clogged the oil passages. I suggest first checking the oil level; if that doesn’t help, switch back to the OEM oil filter. If the noise persists after driving a few hundred kilometers, take it back to the repair shop immediately to check the oil pump pressure.
Don't panic when encountering this issue, let an experienced driver give you some tips. First, identify the type of sound. If it's a metallic knocking noise, it's likely due to low oil viscosity, especially for older cars with over 80,000 kilometers where increased wear gaps require thicker oil. Be cautious with a humming bearing sound, which might indicate accidental impact on the timing cover during operation. Remember to have the mechanic check if the oil drain bolt gasket was replaced – I once had a shop forget to replace it, leading to oil seepage and louder sounds due to low oil levels. A loose air filter box can also cause a sucking whooshing sound. When I first switched to full synthetic oil, I experienced similar noises; it was actually cleaning engine carbon deposits, and it normalized after running through two tanks of fuel. If still unsure, drive back and have the workers check the bearings with a stethoscope.
The loud engine noise after an oil change made me particularly anxious, so I specifically consulted the repair shop owner. He directly asked me if I had used cheap oil from a roadside shop, mentioning that some recycled oils contain impurities that can actually damage the engine. There were also three other possibilities I later understood: during maintenance, the worker might not have properly drained the old oil, causing the new oil to mix with residual old oil and create air bubbles—when the oil pump sucks in these bubbles, it can produce a clattering sound; the oil filter might have been installed too tightly, deforming it or squeezing the gasket out of place, leading to vacuum leaks and unstable oil pressure; the most alarming possibility was a stripped oil pan drain plug, causing a slow oil leak that goes unnoticed as the oil level drops. Now, after every oil change, I ask the mechanic to rev the engine a few times to expel any air, and I also check the ground for oil stains every morning when the engine is cold.
