[MD64]

I have a 2007 323i 6MT that grinds 1->2, and 2->3 when cold, unless I pause for a full second in neutral, in between gears. I bought the car during summer 2015, and the car was not grinding in 15+ deg Celsius weather, but since shifts were awkwardly notchy and not smooth, I flushed the transmission and filled it with Royal Purple Synchromax fluid. Ever since the weather dipped below 15 deg Celsius or so, the car has been grinding the first ~20 shifts minimum.

Now approaching summer, and I'm not sure if I should swap tramsission fluid for OEM or another aftermarket, as I'm not sure if my car will grind with OEM fluid when cold. All the posts I could find about Royal Purple Synchromax were very positive, and, once the transmission has warmed up, I definitely notice smoother-than-stock shifts. Might not be related, but I still have the stock CDV, but I'm thinking of axing it soon. Any help would be appreciated!

On a related note, the car also has really abrupt/jerky compression braking if I quickly let go of the gas while in the 1.5k to 3k rev range in 1st or 2nd gear. Transmission mounts? I check the flex disk (guibo), and it seems to be ok.