Here is my dilemma for all you experts, my MB vehicle uses ZF transmission which recommends the use of non EP ATF even though it is a manual transmission due to the EP oil’s sulphur based additive being corrosive to the soft brass alloy synchros used in the gear box. Now I have access to Mobil-I ATF or GL-5 gear oil. The Mobil-I gear oil is synthetic and therefore doesn’t have the etching sulphur additive package and in terms of viscocity and shear strength, far better than ATF and even their own synthetic ATF.

Should I break the norm and use Mobil-I gear oil in my ZF transmission and get added protection and life or stick to Mobil-I ATF which still would be a far superior alternative to the conventional ATF I have been using so far.