Has anyone used Torco SGO 75w90? I understand that DC calls for GL-5 in the diffs and SGO is rated a GL-6. The only difference I could find on the web is that GL-5 contains up to 6.5% anti-scuffing additive while GL-6 contains up to 10%. I only ask because I have a case laying around in the shop and need to service the diffs. I was planning on putting in Mobil 1 until I remembered I found the box. Thanks in advance.