I just finished changing the oil on my 1993 and noticed that the engine is making a ticking noise, only when I put it in gear, at idle it is fine, but in gear it is ticking. After changing the oil, I let it idle for about 5 minutes to warm up the oil and get it circulating through the engine. I then let it sit and about an hour later I took a test drive and got the engine to operating temperature and noticed that it still ticks even at operating temperature. Any ideas what causes something like this?