Well known fact that the Rotella T 5w40 is a Group III. It is produced from a different process than traditional group III's however. Essentially, it is similar to the process that produces Group IV PAO's, but uses a different feedstock (slack wax) instead of other gases.
The 5/40 is a mix of base oils . I typed in Rotella the right clicked to open the file .
Hydrotreated Petroleum Slack Wax 92062-09-4 65-75%
Hydrotreated Heavy Paraffinic 64742-54-7 10-20%
Hydrocracked HVI " High Viscosity Index " Parrafinic 3-9%
Solvent Dewaxed Heavy Parafinic 64742-65-0
The add pack is the remainder .