Odd sound--any guesses?

[artgirl774]

Once again, you guys are giving me good ideas--so thank you Dan and Precopster--I really appreciate it! Prior to the starter being installed, it wasn't really making this sound (it had noticed it made it very quietly and slightly once or twice that I remember back in June, but became very pronounced after the new starter was put in). The mechanic said that he couldn't be certain it was a rod knock as the sound was not severe at all when he listened to it, but it was there. I drove it to work yesterday and was trying desperately to find a pattern to it. Upon startup in the morning it was quiet as can be, about 2 miles down the road, the noise started up, quietly, then a bit louder. Then after about another 2 miles it got quiet again. My work is only 5 miles away from home, so I sat in my work parking lot and listened to it, and it was soooo quiet--no sound at all. Then when I got out of work, the sound started right up and stayed pretty constant, although throughout the 5 mile trip home it got softer and louder (due to outside speed/wind sounds?). @ Precopster, you're correct, the oil light never came on after I lost oil when they knocked the dipstick tube and o-ring loose. The oil light has come on at startup (with the other dash lights) and stayed on about 1/2 second longer than the other lights, but always goes out and never stays on. I've been pretty regular with my oil changes--purchased in October 2010--Oil change in December 2010, (the car sat with fuel pump and emissions trouble in January), March 2011, end of May 2011 and another one on Tuesday. I do have a few leaks, but they are just a couple small ones--the only major loss of oil was after they knocked that tube loose, but I didn't really drive it during that time, and put oil in it over the 2 day time the leaks occurred. Dan, I'm going to have my husband do your suggested checks as well--thank you for the guidance--I'll post updates as they occur.

[artgirl774]

Hi guys, I figured I would post somewhat of an update (which I would have done sooner, but couldn't due to a family emergency). Well, shortly after my last post at the end of August, the sound mysteriously disappeared. Gone--ran fine, normal, just like the day I bought it. Because the sound disappeared, and we had to leave town, my husband didn't get to do the tests that Dan suggested in his most recent reply (see above in thread). The sound was gone all throughout September, and up until about 2 days ago (approximately 400-500 miles had been put on the car between the sound disappearing and returning) when it returned as I was sitting at a light. Same rat-a-tat-tat sound. I have a small to midsize oil leak and have been adding approx. 1/2 quart of oil approx. every 7 days. Again, no weird sounds at all for the last 5 weeks, but suddenly it's back--very mysterious.