????

Basic bearing metallurgy hasn't changed in over 60 years.

Grease fomulations have improved over the years. They haven't improved to the point that they are more harmful than old greases for same application. What basis do you use to make this statement? All greases I know of are backward compatible. In fact, they are now formulating EP additives that don't attack the bearing metal at high temperatures.

Are you talking about slippage on the bore mount surfaces? I have yet to see the choice in grease affect this phenomenon. Again, what do you base this statement on?

What's wrong with synthetics in the rear differential for ANY vehicle?

Buckwheat, what basis do you use to make ANY of your statements?

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95 E320 Cabriolet, 169K