Why does the RPM increase after changing the engine oil?

[MacJude]

Here are the reasons for the RPM increase after changing the engine oil: 1. The vehicle previously used winter engine oil, which has higher viscosity. This time, all-season engine oil with lower viscosity was used, resulting in reduced engine resistance and consequently higher RPM. 2. It is possible that counterfeit engine oil was used. Using counterfeit engine oil can cause significant damage to the engine, ranging from accelerated engine aging to complete engine failure. Therefore, it is essential to change the oil at reputable automotive maintenance facilities. Here is additional information: Engine oil, also known as engine lubricant (English name: Engine-oil), has a density of approximately 0.91×10³ (kg/m³). It serves multiple functions, including lubrication and friction reduction, auxiliary cooling, sealing and leak prevention, rust and corrosion protection, and shock absorption. It is often referred to as the "blood" of a car. Engine oil consists of base oil and additives.