I decided to pick a few pieces of oak from next years stash, oak which is currently 17 months CSS. IT was lighter in weight and I didn't do a moisture reading. I had a good bed of coals, added the pin oak and it took quickly resulting in purple secondaries for a good long while and loads of heat. Man, I love oak!
The only thing better than 17mo oak is 3yr old oak, but it can/does burn nice. I've noticed a few small splits (3in and less) from 18mos old oak burn just fine.
I CSS some oak logs taken down last winter this june. Curiosity has been killing me so I took a few and put the moisture meter on them. On a fresh split reading 20%. It is stacked in 7 hours of sun and the windiest spot in the yard