I just got my car back from the dealer after an 8 week "odyssey" that all started by Mother Nature playing a dirty little trick on me that eventually cost me a lot of cash.
Anyway, while the car was in the shop, I asked the technician why my transmission seemed to shift even more "notchy" now during the 1-2 shift than it did before they changed the original tranny fluid back in November.
He told me that the Crossfire manual transmission comes from the factory filled with ATF-4 (automatic trans. fluid.) But upon draining it, Chrysler recommended changing it to 05w20 synthetic motor oil. He said using the oil (since it has more viscosity) instead of the ATF, may be the reason the "notchy" 1-2 shift seems even more noticeable now than it did before. Like it did before, after it warms up, it's not as bad.
Supposedly, the synthetic oil is supposed to help prevent or surpress gear/syncro rattle. (Which never was a problem that I noticed with the original fluid).
So my suggestion to anybody who feels their 1-2 shift can be aggravating at times, put some more miles on it, and it may get a little better with age. But unless your tranny rattles in neutral, I'd stay with the ATF.
I'm keeping the 5w20w oil in mine this summer, and see if it gets better with age, (or I simply get use to it) but if it doesn't improve, I may go back to the ATF.
Just my $.02.