Teflon sealant for AN fittings?

If it's NPT then I've used Permatex liquid Teflon tape. You want the yellow looking stuff which is for fuel and harsher chemicals. The white is used for water and oil. I never use the tape as it ends up cracking stuff.

As for AN fittings, never use anything. Maybe wipe your finger in oil and then onto the threads to prevent galling. But most fittings are coated so they won't gall.

Riddler