Since the final finish has been applied to the outside of the frame, it is time to protect the inside. The kit comes with a small can of corrosion preventative compound called Tube Seal. This is the modern day alternative to the old hot Linseed Oil method. I choose to use a squeeze bottle rather than a funnel. After application, both the boom and the cabin assemblies were turned at various angles to facilitate the coating of all the nooks and crannies in the frame. I was surprised on how few pinholes in the welds that the oil wept from.