I've had a startup ticking valve lash noise since new. In Alaska it was particularily noticable in cold weather. Here in NC I also had it but for a shorter time after startup. My oil has always be pristine clean. Since I have switched to synthetic 0w-40 oil I have not had any valve lash ticking, even in cold weather. Maybe changing grades might help.

92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles