In routine car maintenance, many truck drivers find that engine noise increases after changing the engine oil, often causing concern about potential engine malfunctions.
In fact, several common factors are at play. Today, we’ll review the potential causes of increased noise after an oil change and provide scientific advice to help truck drivers address this issue with ease.
1. Overfilling with Engine Oil
The amount of engine oil added must strictly follow standard guidelines; more is not necessarily better. Adding excessive oil increases crankshaft rotation resistance, weakening power output, and increasing fuel consumption.
Furthermore, excess oil can easily seep into the combustion chamber, leading to carbon buildup, hindering piston movement, and reducing power. More seriously, it can disrupt the air-fuel ratio, causing knocking and amplifying engine noise.
2. Incompatible Engine Oil Viscosity
Different grades of engine oil have unique properties, such as low-temperature starting performance or high-temperature anti-wear properties.
Viscosity is inversely proportional to temperature: Oil with excessively high viscosity increases starting burden when the engine is cold, while oil that is too thin fails to form a sufficient protective film at high temperatures, accelerating component wear.
If the vehicle manual recommends using 5W-30 viscosity but 5W-40 is mistakenly used, the noise level may increase significantly. Therefore, choosing the viscosity grade specified by the manufacturer is crucial.
3. Mixing Engine Oils or Using Inferior Engine Oil
Different brands of engine oil use different formulas. Mixing them may cause adverse reactions, altering their lubrication properties, thus accelerating engine wear and increasing noise.
It is recommended that car owners use the same brand of product as much as possible. If a brand change is necessary, ensure the new oil has the same viscosity grade as the original to reduce compatibility risks.
Using counterfeit engine oil is also a common cause. Inferior engine oil is severely lacking in anti-wear, cleaning, and protective properties, causing the engine to bear extra stress, accelerating wear, and increasing noise.
Car owners should learn basic anti-counterfeiting knowledge (such as checking packaging labels and scanning anti-counterfeiting codes) and avoid trusting information from unofficial channels, ensuring they purchase genuine products.
4. Carbon Deposits
As old engine oil gradually thins, carbon deposits will continue to accumulate. When changing to new engine oil, if the engine cannot adapt to the sudden change in viscosity, it may increase the engine speed to compensate, resulting in noticeable noise.
It is recommended that car owners use high-octane gasoline and maintain a higher engine speed (e.g., above 2500 RPM). This should improve the situation after one tank of gas. Regular preventative cleaning can also effectively alleviate this problem.
5. Normal Phenomenon When Cold-Starting
When starting a cold engine, most of the engine oil flows back to the oil pan, resulting in insufficient lubrication of components. Combined with the low temperature affecting oil performance, the engine speed is higher during warm-up, and the noise is normal.
Noise usually decreases naturally after the engine warms up. However, if the noise persists after warming up, it is recommended to have the engine inspected at a professional repair shop as soon as possible.
6. Subjective Perception Bias
In some cases, changes in volume are psychological. The sensitivity of the human ear varies greatly in different environments, so judgment should not be based solely on feeling.
Technical analysis shows that 5W-20 or 5W-30 viscosity engine oil produces slightly more noise in urban driving and less noise at high speeds; while 5W-40 or 5W-50 viscosity oil produces lower noise in urban driving and more noise at high speeds. Objective data can be obtained using a decibel meter.
If the noise increases after changing the engine oil, the owner doesn’t need to worry excessively. Usually, the noise will disappear naturally after a break-in period.
If the problem persists, a professional inspection at a repair shop is recommended. Truck maintenance is not only a technical skill but also requires a rational mindset and scientific methods.
