I'm looking to install a Eaton/Detroit TrueTrace Torsen differential in the near future. The owners manual states:
High quality mineral gear lubes are required for use in
Detroit Truetrac differentials. Regardless of the lube
type, always use a GL5 rated lube with the least
amount of friction modifier. Mineral lubes lacking
friction modifiers (limited-slip additives) were
historically recommended for all Truetrac applications
because friction modifiers can slightly reduce the bias
ratio (limited-slip aggressiveness) of Truetrac
differentials. However, to address the continually
increasing power outputs of modern powertrains, many
vehicle manufacturers have switched to synthetic
lubricants as a counter measure for increased axle
temperatures and prolonged service intervals. In
general, consult the vehicle owner's manual for the
manufacturer's recommendations for lubrication type,
weight and fill volume. This will ensure lube
compatibility with the seal materials and bearings used
in the axle. Eaton Performance technical support is
available for any concerns in lube selection.
The factory fill recommendation for the OEM rear-end is a synthetic 75W90, but the factory differential was not a Torsen design. I'll be using either the OEM axles, or aftermarket replacement axles. Some are saying "140 is too heavy for a Torsen. No manufacturer will recommend an oil that heavy, it will change the friction levels the diff relies upon to function to its fullest", while others are saying the 140 will reduce noise. Application will be daily driver that sees some autocross and HPDE sessions (20 minute sessions of limited passing).
I've found the following gear oils without friction modifiers, should I consider any of these or look elsewhere?