It used to be usual to wet paper or thin cardboard gaskets with engine oil before installing them. The idea was to make a wet seal on both sides of the gasket, so it would be less prone to leaking and more likely to be dismantled without breaking the gasket. Remember, though, that in those days you expected all submerged gasket joints to leak a bit. The world has changed, more due to the design efforts of Honda's car division than from any other single cause that I know of.
