Thanks all.
I think everyone is fine if someone does not want to use a sealant on their lines, copper flares should seal almost all of the time if done right, good luck.
The Nylog is not a thread sealant, though works great as a thread sealant, rather it is designed to seal more than that.
It looks and feels like snot, and it does not dry ever, and does not blow out. This is not a glue, but more of a gasket that remains tacky and liquid, but will restrain very high pressures.
Adding Nylog to a connection that does not require a sealant is harmless, and will ensure you have the best and most long lasting seal possible.
I have been able to re-use crush washers because of Nylog with no leaks.
On my current new copper piping the Nylog even held pressure with just a hand tightening of the flare nuts, something that could never ever happen without it.
I highly recommend using this product on your pipe fittings.
There are two types, Red and Blue. I use the Red for this application.
It is also "food safe" and used in the refrigeration industry on large units.
I do not work for or represent the brand, but just sharing good info.
I got mine on Ebay for about $9. thanks