Removing axle half shafts, 124 car
I removing the axles to swap differentials on my car from one in a parts car. On my daily driver, the axles came out Okay, the output flange of the diff was clean. One or two bolts had some grease/oil on them.
On my parts car, which hasn't been driven for 2 years, more of the bolts had grease/oil on them, the output flange had some light surface rust in the middle, and there was a strong smell that I had never smelt before. Same potency as gear lube, but slightly different smell.
Q, should I do anything about the surface rust in the middle of the output flange, or is it Okay to leave it?
Q, why the oil/grease on the bolts?
Q, what is the best way to clean all around the metal of the axle shafts and differential, if any?