What specifically needs the 507? 504 and 507 are considered interchangable as they are both low SAPS for aftertreatment component life and meet Euro IV. At least thats my understanding and why the 2 are combined approvals on lots of oils, ie; 504.00/507.00. Also, these approvals are almost all 30wt and you won't find a 40wt. easily if at all.