What is the best kind of additive to add to your tranny to help with the shifting out there?

 

A good ATF (synthetic?) and proper servicing.

 

Lucas TRANS/Fix. I have heard dozens of testimonials from people with shifting problems (on automatics). Change filter and old fluid, add fluid and trans./ fix and drive easy for 30 minutes.

You may want to pour bottle of trans./fix into pan before installing pan. Trans./fix is very thick.