At the risk of boring the OP to death: The new CK spec applies specifically to Shell T5 and T6 Rotella, per this Shell FAQ statement:
- Will the new FA-4 specification only apply to T5 and T6?
The FA-4 specification will only apply to Shell ROTELLA® T5 Synthetic Blend Technology heavy duty engine oil and Shell ROTELLA® T6 Full Synthetic heavy duty engine.
This means the T4 spec you mentioned below shouldn't have changed (and pretty much didn't). The new CK-4 Rotella T6 I use in my Ford 7.3 PowerStroke (IH) diesel no longer has near as much zinc, etc., so I bought up some older CJ4-spec oil and will use that until I run out. Ford got a big wedgie over the CK-4 spec and would not back its use in any Ford diesel until just recently.
Not meaning to start an oil war in this thread. The whole topic is more confusing than modern antifreeze, fer crying out loud. Good reading on the oil spec here:
2017_04 - April 2017 - LNG
Steve