1986 Volvo 240 Thread sealant or not?

Replacing oil pressure sender. Threads are 1/8"-27 NPT into an adapter for M14x1.5mm into the block. No external electrical ground connection on the sender, so it gets its ground through the threads. Some say I'm supposed to use thread sealant to prevent oil leaks. Some say don't use sealant because it will interfere with the ground. Which is it? Thanks.