If you're talking about the rocker arms and not the lifters, the roller rocker arms should not affect how long it takes the oil to get up top.
Can you hear the bearings rattling when it first starts? If not I wouldn't worry about it. Why the heavy oil? Try a lower viscosity oil. Heavier oil takes a little longer to establish pressure.
When the engine hasn't been fired for a long period, pull the coil wire and ground it out or disable the ignition and crank until oil pressure is established. Then enable the spark and fire her up.
Squido
Can you hear the bearings rattling when it first starts? If not I wouldn't worry about it. Why the heavy oil? Try a lower viscosity oil. Heavier oil takes a little longer to establish pressure.
When the engine hasn't been fired for a long period, pull the coil wire and ground it out or disable the ignition and crank until oil pressure is established. Then enable the spark and fire her up.
Squido