What are the signs that engine oil needs to be changed?
3 Answers
The signs that engine oil needs to be changed are: 1. Check the oil quality—if the color turns black and it smells acidic, the oil needs to be replaced; 2. Use your finger to check if the oil still has viscosity; 3. Difficulty shifting gears when starting the car cold. The method for changing engine oil is: 1. Remove the air filter, clean it with an air pump, and reinstall it; 2. Lift the car, unscrew the drain plug to release the old oil, and remove the oil filter; 3. Add approximately 3.5 liters of new oil. The functions of engine oil are: 1. Reducing friction and high temperatures; 2. Cooling and lowering temperature; 3. Cleaning and removing contaminants; 4. Dampening vibrations and shocks; 5. Preventing rust and corrosion.
I remember the mechanic mentioned during the last service that there are three main signals for oil change: First is mileage – conventional mineral oil should be changed every 5,000 kilometers, while full synthetic oil can last up to around 10,000 kilometers. Second is time – even if the car hasn't been driven much, the oil will oxidize and deteriorate after about six months. Third is routine dipstick checks – if the oil turns as black as coffee grounds or becomes as thick as honey (forming strings when pulled), it's time for a change. Additionally, if the engine sound becomes hoarse or fuel consumption suddenly increases, these could also be signs of aging oil. Old Zhang in our neighborhood delayed his oil change, ending up with an 8,000-yuan engine overhaul – definitely not worth it.
I generally follow the maintenance manual for my car, but also adjust based on actual driving conditions. For regular city commuting, I change the oil when the dashboard maintenance reminder appears. If I've recently taken long trips or frequently driven on mountain roads, I'll inspect it half a month earlier. Once after a road trip to Inner Mongolia, I noticed the engine oil was particularly black. The mechanic explained that sandy/dusty areas accelerate oil contamination. Now I've developed a habit of checking the dipstick monthly - healthy oil should be amber and transparent. If it's dark with metal particles, immediate replacement is needed. During my last maintenance, I learned a useful trick: drip oil onto a tissue paper - uneven color dispersion in the spreading ring indicates it's time for a change.
