The old rope seals worked great and lasted a long time. They switched materials at some point in the 90's? and they don't last as long any more.

I ran rope seals in all of my pontiac engines (350, 400, 455) for years except my newest ones i went to a viton 2 piece seal, less drag.

 

The rear main seals on these engines may be vulnerable to long periods of non-usage.

When my dad bought my truck new he purchased the 7-year 70,000 mile extended warranty from Dodge. At slightly less than 7 years (and about 44,000 miles) the rear main seal began leaking and was replaced under warranty.

 

Amen!! This is true of all mechanical things that are lubricated by some kind of oil and sealed up with some kind of seal, rubber especially. They are designed to be used and that usage is an integral part of the design. They are like thoroughbred horses, they die slowly when they are not run, all my opinion of course...Mark