BigRigTech
Diesel junky
ZF's are notchy on a good day, I drive mine like Goofy described, much easier on the trans and it will prolong the life span. I drained the reg ATF out of my ZF and filled it with syn ATF....Mistake....Now I have to be going very slow to downshift into 2nd gear....With the reg ATF it could be done at any speed within reason. My trans works great and I thought the syn ATF would make it shift even better....It does but not being able to downshift into 2nd like I was used to doing really ****'s me off so I'm going back to reg ATF.