What are the reasons for oil around the engine oil cap?
2 Answers
The reasons for oil around the engine oil cap are: 1. Poor sealing of the oil cap, which may be caused by aging or human damage to the sealing strip; 2. Oil was spilled around the filler port when adding oil, and it was not thoroughly wiped clean (to clean it thoroughly, gasoline or cleaning oil must be used to wash it at least three times). If it is caused by the first reason, it must be repaired in time. The method is: replace the new oil cap assembly or replace the sealing gasket, otherwise it will lead to excessive oil loss, and in severe cases, serious failures such as bearing seizure; if it is the second reason, it is just unsightly and will not cause other consequences, as long as it is wiped in time, it can be solved.
I often see people asking about oil stains around the oil cap in car owner groups. The main reason is that the pressure or vibration generated during engine operation loosens the cap. If the cap's sealing ring ages or breaks, oil will leak out. Another common cause is a clogged crankcase ventilation system, where increased pressure forces oil out, especially in older cars. I once experienced this myself—I forgot to tighten the cap, and oil residue built up, making cleanup a hassle and nearly causing engine overheating. I recommend immediately checking if the cap is tightened, replacing any damaged sealing rings, and cleaning the surrounding oil stains. During regular maintenance, have a professional test the ventilation valve to prevent small issues from escalating. Engine oil leaks are no small matter—neglecting them can reduce performance or even pose a fire risk, so always wipe off any spilled oil carefully when refilling.
