My car had trouble with 2-3 shifts. Anyway, I changed the fluid with Pennzoil ATF synthetic blend and added the friction modifier. Now I can barely get it into 1st or 2nd, until the car warms up.

I got some Mobil 1 ATF, which I'm gonna try this weekend. Do I still add the modifier? What's this stuff really do? The bottle says to quiet gears in the rear......

PS
I got this filler from Walmart that goes on the end of the bottle, and has a release thing to let the oil out after the bottles upside down and the end is in the fill hole - makes life easy, especially as I try all tranny cocktails