I would advise caution applying anything that sets to an o ring to help it seal, especially if there is movement or alignment issues in the joint.The whole concept of o rings is that they deform in a controlled manner and if you put in some liquid gasket material that may then turn hard, you may effect the o rings chances of sealing under vibration or movement with heating and cooling.
I have found that some decent lube on the o rings so that they seat happliey is the most important factor.
You have to have happy well lubricated o rings!!
No warrenty expressed or implied by these coments! If it works for you go for it.