Don't go with the dual rated oil.
10W30 diesel oil CK4 fine, or 5W40 for LS engine.
Dual rated takes all the good additives out of the oil to appease the API.
The only reason why T5 and T6 arn't "dual rated" or don't carry an SN rating, the additive level zinc phos is higher than the allowable limit for SN. The formulation and additives have't changed only the specification changed for allowed limit in API SN. Hope this helps.