Single-digit HD! I mean, it's still got seven, and it's ooze-type, but we're getting closer to playable stuff!
Conflagration oozes have the aforementioned bad HD, okay-ish stats (at least they lack the abysmal stats and mindlessness of most oozes), two reasonably powerful slams, Large size, DR 5/bludgeoning (which really seems like it should be slashing and piercing), and improved grab. Grappling is still kinda viable at those levels, but it should be noted that a lot of monsters already have grapple checks in the mid-twenties.
Speaking of grappling, the ooze has a special ability that lets it turn stuff it grapples into liquid fire. Kinda. Ineffectively. That said, free damage is free damage, even if 2d6 fire and 1d4 constitution are on the low side. Free Ability Focus helps with the DC, though.
Finally, and somewhat surprisingly, the conflagration ooze can use Deep Slumber, Confusion, and Hold Monster once per day each. As far as SLAs go, they're decent.
While I think an argument for +0 could be made, in the end I'm going to assign -0. After all, using weapons and equipping items will be a challenge in itself, grappling is kinda weak as far as strategies go, and the SLAs aren't great either.
Infernal Conflagration Ooze
Literally a standard specimen with more HD and the fiendish template. -0 LA.