Not necessary if your fittings are new or undamaged. If you must use something due to bunged threads or something, use Permatex Seal Lock.

It is a combination of blue thread lock and thread sealer.

https://www.amazon.com/Permatex-57535-Seal-Thread-Compound/dp/B0787N1LTY/ref=asc_df_B0787N1LTY/


1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)