I am prepping the rear axle that was rebuilt for my project. It is from a '94 Mustang GT - converted to Fox width with new Moser 5 lug axles, rebuilt trac-lok, new FRP 3.55 gears, bearings, and seals. I bought some Royal Purple MaxGear 75W-90 gear oil for the axle. It says "with friction modifier additive" on the label. So, I do not need to add any Ford Racing friction modifier to the axle - just the Royal Purple? I don't want to damage the fresh differential mechanicals. Thanks.
John S.
Mk4 Roadster 8866