Why Can't the Oil Cap Be Unscrewed?
2 Answers
Oil cap can't be unscrewed due to negative pressure and being tightened too much. To add engine oil, you must open the engine hood. Besides the oil cap being difficult to open because of the high suction caused by the lack of air intake under negative pressure, it could also be due to the oil cap being too tight. You can wait until the car cools down before trying to open it. If it still can't be opened by hand, tools like pliers can be used. Here is some related information: Engine oil is the source of a car's power. It plays roles in lubrication, sealing, cleaning, heat dissipation, buffering, and rust prevention within the engine. Changing the engine oil is a must-do item in car maintenance. By unscrewing the oil pan's drain plug, the old engine oil is drained, and then new oil is poured in, completing this maintenance task.
It's quite common to encounter a situation where the oil cap won't budge. As someone who frequently works on my own car, I've faced this issue many times. The most typical causes are either the cap was over-tightened last time or the threads have rusted. After the engine runs and heats up, the metal expands and then contracts as it cools, making the cap prone to getting stuck. This is especially true for older vehicles where improper maintenance leads to rust buildup, exacerbating the problem. My advice is to avoid over-tightening the oil cap during oil changes—hand-tight is sufficient. Afterwards, applying some anti-rust oil or lubricant to the threads can prevent rusting. Also, try opening the cap when the engine has cooled down rather than when it's hot. If it still won't open, use a wrench with a towel for better grip and apply steady, even pressure to turn it slowly, but don't force it to avoid damaging the cap. Regularly checking and cleaning the threads can significantly reduce this hassle; otherwise, over time, the cap might become unusable. I've found that paying attention to these small details makes subsequent repairs much easier and saves on costs.