Pretty low shear quality on modern ATF. Lock-up torque converters took the need for that out of ATF, and the quality is lower, as a result. Very high detergent, not really needed in a gun application.
Not my first choice, but, likely better than what was available when the guns were new.
Chuck is likely on the right track. My Dad put 150,000 on a 1951 flathead Ford, using straight mineral oil of whatever quality was available back in the day-but, he changed it at 1500 mile increments.
I'm going to boldly guess if you are on this site and reading this, you are in your gun often enough it really doesn't matter what you use. Fresh lube will keep 'em running longer than it will keep us running.
Anyone here ever worn out a gun?
Best,
Ted
