Need your advices on wroing with O ring
 

About to R & R the dryer to condenser A/C Hose. I know both ends has an O ring. My question to experts here are:

1) how hard should I tighten here?
2) do I need to use some sort of lube/sealant on O ring?

Your comment will be greatly appreciated.

Not knowing the vehicle:

1) Back-up wrench on condensor fitting (if like mine); "snug" it up, but remember, you are dealing with soft metal on the condensor.

2) Use Nylog or refrigerant oil on the "O" rings.

always remember backup.