Spin ice materials are a class of compounds with exotic magnetic properties, resulting from the frustration. Magnetic monopoles have been detected at low temperature; manifest as quasi-particle excitations. A specific heat study of the natural abundance of Dy2Ti2O7 found an upturn at long timescales (>10000 s) below 0.6 K, suggesting the emergence of previously unobserved ordering, and the break-down of the spin ice phase. We have studied the specific heat of 162,163 and the natural abundance and find no evidence for this phase transition. However, when we implement corrections for the hyperfine interaction, we find some difference between 162 and 163. One explanation for the difference in specific heat is a difference in the oxygen defect structures. Having already studied 162 on SXD, we propose a diffuse scattering study of 163 to explain our data.