A soft-set thread seal is required for a tight non-leaking connection when using NPT threads. All nozzles and accessories that have NPT threads require a thread seal. Jomar Heavy Weight thread seal won?t break down when used with any of today?s unleaded fuel blends. Also, a soft-set thread seal will not harden so you can unscrew the items later for replacement or repair. When sticking your tank, you may use a color changing gas finding paste to help determine the exact liquid level as marked on the tank stick. Water finding paste can also be applied to gauge any water content in your fuel.