I broke my TKO 600 in with ATF and at 500 miles I changed the fluid no metals shavings. I refilled with ATF (Dexron) and added 2-3 ounces of Lucas
Oil and 5000 miles later the tranny shifts great . It quick shifts fine too. And, I don't baby the car either.
I did have major clutch issues and shift problems until I bought a Quiktime Bellhousing and got rid of the Lakewood boat anchor . I have Forte's hydraulic cylinder and my clutch/shift issues went away .