Those shop manuals & owner manuals are reprints from the originals when multiweight oil was not invented yet. Much has changed in the industry since then. I didn,t know about the cam wear problems with the preasant car oils till they were talked about on this websight. I am now using the diesel oil in all my flat tappet engines. The Shell Rotella & similar oils only come in 15W40 which is good in anything except real cold weather.
