Howdy All:
Scotty- With a engine this old (42) and this many miles (153k) there is a strong likelyhood that the oil channels in the rocker arm stancheon and shaft and the orifaces in the rocker arms are completely plugged. If so, no brand of oil or additive will reopen them. Oil and additives have to be able to flow to and through the gunk to have a cleaning effect. Low oil pressure adds to the ability of the oil to flow through narrowed passages. If a plug exists nothing short of disassembling, cleaning and coring will re-establish oil flow.
The simplist test to verify oil flow to the rockers is to remove the valve cover, preferably on a cold engine. THen start the engine and watch as the oil oozes out of each rocker arm, from the rear to the front rocker. IF it takes more than a few seconds to get oil to the front rocker arm, you will know that there are some restrictions, but that a detergent additive may be effective in cleaning internally. IF you don't see oil ooze at all rockers within a few minutes that will be a strong indication that there is a plug in the system.
THe next step will be to remove the rocker arm shaft and stancheon, dissasemble and clean. Closely inspect the pushrod balls for signs of wear. I've seen both a nipple on the top where the pushrod was still rotating, as well as a ridge where the pushrod no longer was able to rotate due to lack of oil. There is a "sticky" at the top of this forum on how to disassemble and clean the shaft and the rocker arm oil holes. This along with replacing worn parts should have you "tickless" again.
Check it out and bring us and update.
Adios, David
