Looking at doing a gear oil change on my 1994 dodge ram with the Cummins. Front dana 60 and rear dana 70 with a limited slip. While I'd like to run redline, shaeffers, or amsoil, those are simply out of my price range. How does the Delo Syn-gear look? I've read the SDS (https://cglapps.chevron.com/sdspds/SDSDetailPage.aspx?docDataId=426535&docFormat=PDF) and can't tell if I still need to add friction modifier. Your thoughts and experience is welcome. Thank you.