69 Z/28 Day II Project (Air Force Brat)

[big gear head]

Use that oil for break in and then put this in it. https://www.amsoil.com/p/manual-tran...AaAj9iEALw_wcB
I had an oil related failure in my M23 when using the Driven oil. The synchronizer engineer from New Venture Gear, who is also working for AutoGear as a consultant, told me that they had done a lot of testing and the Amsoil MTG was the best that they found and recommended that I use it. So far it's working great. Also pay attention to AutoGear's oil capacity recommendations. Don't fill it to the bottom of the fill hole like you would a Muncie. If you plan on running it hard then you will need to modify the vent or you will have oil running out. It's best to fix it now before it's in the car. Use a 90 degree fitting in place of the vent and run a hose toward the front of the transmission with a vent in the hose. Under hard acceleration oil will come out of the standard vent.