I have H23 prelude with 96k mi. The car idles perfect but when I open the throttle to about 1-1.5k rpms there is a moderate ticking sound coming from the head, when 1.5k rpm + the sound goes alway. I narrowed it down to the area right under or next to the oil cap. I can't hear it when I drive, but when I'm doing some work under the hood it is very clear; the engine runs great at all rpm's. Is this a common problem on a honda engine? and is this something that I should be concerned about? I'm not sure what kind of oil that is in the car, the previous owner told me that it was light synthetic. Maybe some heavier oil would cure this, any help is appreciated