I have a 1996 Honda Civic, 1.6L D16Y7 non-vtec engine, 5-speed manual, 207,000 miles. I have had the car since fall 2010, and put 51,000 miles on it. I first heard this ticking noise after the engine was started one time when it was really cold out, but it went away quickly. I had Valvoline conventional 5W-30 in there at the time, and I have been running Purolator Pureone filters on it the whole time. After that, I don't ever recall hearing a noise until fall of 2011. I had Pennzoil Platinum 5W-30 in it at the time, and I was consistently hearing a ticking noise for a couple minutes after start up. So I drained the PP, and put in Mobil Clean 10W-30. It quieted down maybe 20%, so it seemed quite a bit better compared to what it had been. The noise no longer sounded like high pitched tick, and more like a deeper knock/tick. Then I tried a 5W-30 again, and the noise went back up. So switched it back again. Since then I've tried lots of oils and tried to get the noise as quiet as possible. This fall, the noise was quite a bit louder than fall 2011, so it seems to be getting worse. Here is a list of the oils I've used and the experience that I had with them. 1. Valvoline Conventional 5W-30 (Small tick one time) 3000 miles, October-December 2010 2. Mobil Clean 5000 Conventional 5W-30 (No Noise) 3000 miles, January-March 2011 3. Quaker State Ultimate Durability Synthetic 5W-30 (No Noise) March-August 2011 4. Pennzoil Platinum Synthetic 5W-30 (No noise when it was summertime, significant tick when weather turned cold) August-November 2011 5. Mobil Clean 5000 Conventional 10W-30 (Less tick, takes longer to start ticking) 3500 miles, November 2011-January 2012 6. Super Tech (Mobil) Conventional 5W-30 (a little louder tick) 7. Back to Mobil Clean. 8. Valvoline and Quaker State Conventional Mix 5W-30 (Quietest the car has run recently, quieter than Mobil Clean) 4000 miles, April-June 2012 9. Mobil Super Conventional 5W-30 (Sounds like super tech, kind of loud. At the end of the oci, I drained 1 QT. and added 1 QT. of Rotella 15W-40 to see if a thicker oil would help, seemed to make it very slightly worse) 2500 miles, July-September 2012 10. Back to Mobil Clean 10W-30 (Quieted down compared to Mobil Super, but got louder as it got colder) 4000 miles, September-December 2012 11. Havoline Deposit Shield 5W-30 + LubroMoly (A little quieter than the Mobil Clean) 2000 miles so far. I have not yet tried using 15W-40 HDEO, but I kind of doubt it would help. The noise is coming from the block area, and not the valvetrain. It does it especially at about 1700-2000 rpms just idling when cold. It is louder the colder it is outside (loudest when below 30 degrees, you hear some pretty sharp knocks for about 10 seconds), and gets pretty quiet when its above 65 degrees overnight. If you try to drive it when it's still cold, you hear it somewhat loudly in the 2100-2400 rpm range. Once the engine warms up you don't hear any noise until the engine has been running for quite a while, and you only hear it very faintly if you have the windows open when the transmission is in 2nd gear, and about 2100-2400 rpms. So, I'm pretty puzzled at what this noise is. I read that it could be a rod bearing knock, but would the car drive for 51K miles with a rod knock, and only get a little bit louder? I don't know, and am very curious if this is possible to happen or not. Another possibility, could it be piston slap? The noise sounds kind of like this video when the engine is cold, and you rev the engine: http://www.youtube.com/watch?v=HZ9JLcW6FoI Sorry for the long post, but I would greatly appreciate any advice you could give on what to do. Thanks in advance.