Banjo's recommendations are as follows:
We DO NOT recommend using pipe tape. Pipe tape enlarges the outside diameter of the male thread and may cause the female thread to split.We recommend using a pipe thread sealant. Use on clean tapered threads. Apply a thick even coat on male threads using brush applicator. For pipe diameters smaller than 1¼" apply to male threads only. For 1¼" and larger sizes apply to both male and female threads. Avoid applying excessive amounts. Hand tighten joints and then torque another ½ to ¾ turn until threads seal.
RectorSeal® No. 21™: This is a slow drying, soft set multi-purpose sealant designed for use where black is preferred. 8 oz. can with brush in the cap. Conforms to TT-S-1732.
RectorSeal® Tru-Blu™: This is a fast drying, flexible set thread sealant designed for high vibration environments. Teflon®* has been added to enhance thread lubrication during assembly and break out. 8 oz. can with brush in the cap. Conforms to TT-S-1732.