If your car's oil cap is stuck and you can't get it off, there are a few things you can try. First, make sure the cap is turned to the unlock position. If it's still stuck, you can try using a rubber band or a piece of string to get a good grip on the cap and twist it off. If that doesn't work, you may need to use a pair of pliers or an oil filter wrench. Be careful not to damage the oil cap when using these tools. Once you've removed the oil cap, be sure to clean any dirt or debris out of the threads before screwing on the new one.