Do Oktavists Use Subharmonics?

As far as I'm aware though, oktavists' lowest notes are all modal; no fry, no "subharmonic" manipulations of the cords, rather their voices are simply able to go that low.

Are Subharmonics bad for your voice?

Why you should use this technique

This technique sounds better than vocal fry in that it is louder, more resonant and sounds nicer, as well as that it does not cause damage to your vocal chords. In a capella singing it may be tricky to use for a novice, but for choral singing this can be used in amazing ways.

How do Octavists sing?

With octavists, most of them use harmonics in singing, it's pretty obvious when it's being done as the singer with have a REALLY reedy sound to their voice. The technique involve doesn't involve swallowing, it's a type of vocal fry (I'm not kidding, I actually can do this!).