Why Does the RPM Increase After an Oil Change?
2 Answers
Reasons for increased RPM after an oil change are as follows: 1. Oil is too thick: When the oil is too thick, the engine requires a higher idle speed, known as fast idle. At this time, due to excessive resistance, the fuel injection volume increases. Moreover, during fast idle control, its idle learning value needs to be adjusted upwards. 2. Excessive carbon deposits: High RPM is generally caused by excessive carbon deposit accumulation. Timely cleaning of the throttle and idle speed motor can usually resolve the issue. 3. Overfilled oil: If the engine oil is overfilled or an excessive amount of oil is accidentally added without proper handling, it may lead to oil burning, especially at high RPMs. This increases the engine's workload, resulting in faster engine RPM.
Last time I changed the engine oil myself, I encountered a similar issue where the RPM inexplicably rose to over 1,000. Later, an experienced mechanic told me that overfilling the oil can cause the crankshaft to be submerged, creating resistance that the engine compensates for by increasing RPM. You should first check the oil dipstick level - if it's above the maximum mark, you'll need to drain some out. Another possibility is using the wrong oil viscosity; putting 5W-40 oil in a car that requires 0W-20 for winter can make it too thick. Also carefully check if the oil filter is properly installed or if the gasket is deformed and leaking. Don't jump to conclusions about engine trouble - new oil has fewer impurities and better lubrication than old oil, and the ECU needs some time (dozens of kilometers) to adapt. Finally, if the RPM remains high after idling for three minutes, immediately return to the repair shop to scan for trouble codes.
