Reviewing the old and new T6 5w40 specs and noticed the pour point has improved from -42 to -51 degrees Celcius! This indicates different base oils, especially considering the oil has a higher viscosity at both 40 and 100 degrees celcius. HIgher flash too.
CJ-4
http://s7d9.scene7.com/is/content/GenuinePartsCompany/1843126pdf
CK-4
http://www.purseroil.com/wp-content/uploads/pdf/ShellRotellaT65W-40.pdf
And in case it hasn't been posted, the new CK-4 T4 15w40:
http://oilmart.com/data/products/pds/142/TDS Rotella T4 Triple Protection 15W-40.pdf
I'm starting to lean towards this for the wee after I get through my current CJ-4 stash due to the very low VI and shear stability.
CJ-4
http://s7d9.scene7.com/is/content/GenuinePartsCompany/1843126pdf
CK-4
http://www.purseroil.com/wp-content/uploads/pdf/ShellRotellaT65W-40.pdf
And in case it hasn't been posted, the new CK-4 T4 15w40:
http://oilmart.com/data/products/pds/142/TDS Rotella T4 Triple Protection 15W-40.pdf
I'm starting to lean towards this for the wee after I get through my current CJ-4 stash due to the very low VI and shear stability.