Recent content by Mowendevlin

The book actually specs for ATF on both and to my knowledge I think I drained the factory original fluid. Amsoil specs this oil for the application. All I could do is try going back to a conventional ATF unless I try a different fluid outside the spec.

I recently changed oil in my 1997 F350 (60k miles) with a ZF5 and a 2004 F250 (120k miles) with a ZF6 manual (both gas engines). Both of these operated and shifted flawlessly before and the fluid changes were both done as preventative maintenance. I filled them both with Amsoil Torque-Drive syn...