Use one or the other, NOT both together. It's possible to starve a valve guide for lubrication by too much sealing, resulting in wear, galling, or actually sticking of the valves. The original method was a sheet metal shroud around the top of the valve spring, and a rubber O ring around the stem to prevent oil from leaking down the valve stem. An alternative method was to remove the metal shroud, and add an "umbrella" seal that fits tightly around the valve stem, and rides up and down with the valve. This seal sheds oil off the top surface, preventing oil from puddling on top of the valve guide. The third method is the "positive" seal, which clamps to a machined shoulder on the valve guide, and wipes oil off the valve stem as it passes through a spring-loaded lip on the seal. Use only one of these types of seal, don't double up on them.
With good, tight valve guide clearances, all that's needed is the original O ring system. Somewhat worn guides can benefit from the umbrella or positive seal systems.
Jerry
