I have had 2 507's. Both ran on SAE 30. I used Rotella. Since it is your first service, there is a small screen filter that should be checked ( a great place to see first signs of trouble). And the oil you take out should be clean and not smell " burnt". Lastly and it should be marked on the dipstick, check the oil running, at idle, prefferably warm. That, in my opinion, is one of the most bulletproof transmissions ever made- it should serve you well!