Gotta a question for ya', Ags! This oak is about 30 years old. Starting to see cavities show up on the trunk. The one near the bottom of the tree is soft in the center, but solid around the edges. Any idea if what I'm looking here and what I need to do? If hate to lose this tree... We're in Central Texas, just north of Cedar Park.

Growing around a dead spot....not a good situation. I'd cut it down before the rot and wind takes it down. Best time to plant the replacement is yesterday.

That is a Monterrey Oak & it probably received some pretty good freeze damage the past few years - in addition to some bad droughts. I don't think this tree is 30 years old, it looks about 1/2 that IMO.
Monterrey Oaks only became available in the nursery trade about 30 years ago, I doubt this is one of them.

I personally would leave it up & plant a replacement nearby just in case.

I planted it in the early 00s myself. It might have been in a 5 or a 10 gallon pot I put it in the ground...

And yes, it (and all its buddies) have taken a beating over the past couple of years.

Anything I should or can do to try to treat it?

I would give it extra water & a nice layer of compost around the dripline in the spring.

Keep an eye on any boring insects, carpenter ants, etc. that are going into the exposed heartwood & treat immediately.

You also want to thin out the canopy gradually to reduce the weight (and thus stress) above & around the damaged areas.
Make sure you don't have a sprinkler head blasting the trunk with water 2x per week. That will speed up rot to the heartwood.

In the old days, you'd do a cavity fill.... that is no longer considered good practice. Your tree has healed around the wounds which is about as good as you can ask for. At this point closely monitor & try to reduce stress w/the methods above.

Thank you!

Paging two1993ags!