Also, does anyone know if Valvoline Restore and Protect ATF has seal conditioners in it like MaxLife is supposed to? I'm thinking about sucking some Dexron VI out and replacing it with MaxLife to see if that helps with my slip in 3rd until it's warmed up. Read somewhere that sometimes old seals can prevent adequate pressure from building, which resolves once fluid expands. Which could be why overfilling slightly has helped.
Didn't see anything on Valvoline's site about seal conditioners in Valvoline Restore and Protect. And I know a conditioner might not fix bad rubber, but figure a little couldn't hurt trying.