Ok here is the skinny. I have a 91 Corolla. I noticed that my oil was low, so I added a quart. No big deal done this before. It has over 308k on it so using a quart every 3 month or oil change isn't too bad I figure. Anyhow I closed the hood then had to run to Wal-Mart which is about 10 miles away, by the time I got there it was studdering and acting like it was gonna die at any moment. I managed to get out of trafic and into the parking lot, to discover I'd forgotten to put the oil cap back on. Yeah I felt like a complete moron. I put oil back in it but now it sucks gas like there's no tomorrow and it sounds horrible. Like a mini tank. There is a loud ticking, tapping, almost knocking kind of sound. What did I break? And more importantly how hard is it to fix and how much? It runs but I don't run it unless I really have to. Any info at all would be most helpful. It's my only car so I'm rather depandant on it.