MC2500 oil and TW25B grease. I first started in the '80s when I went for some training on M61 Vulcan guns at the GE factory in Vermont when GE still made the guns. GD makes them now. Anyway, the techs and engineers there recommended the Mil-Tec products.
They had a remarkable range that I think they shared with National Guard. The backstop was a whole mountainside.