Quote Originally Posted by HoustonRemodeler View Post
FWIW we ONLY install 1/4 turn ball valves.
Me too, far less failure rate, easier to use, last longer, so worth the effort.

With a standard valve style (twist and twist and twist to open/close ) I follow the same regimen as Mastercarpentry, and that is to open them fully, then back off 1/4 turn, or so. This prevents distortion of the stem washer, it also gives you room to "fine tune" a valve stem that wants to leak because it's been moved out of its "sweet spot". Another trick is to carefully tighten the stem nut ever so slightly, this squeezes the stem washer a touch more and usually makes the seal.