Question on running Synthetic Trans oil in '94 E320
 

I am doing a trans, torque convertor drain and filter replacement soon on our E320. I was wondering if anyone has tried full synthetic or semi synthetic trans oils and what you think.
I have a 2001.5 Dodge-cummins powered and had the trans beefed up. The builder installed just Dexron 3 where the manufacturer called for a semi synthetic ATF +3. When I serviced it after the rebuild, I put back in the ATF+3. It shifted alot more solidly.
SO.... Can I run that in the MBZ??

Yes, in that year & model.

I'm planning to do the same job on my '92 300E soon. Same question: Can I use full or semi-synthetic or should I stick with just regular ATF?

Also, it has a rather hard 1-2 shift, especially when the a/c is on. Is there an easy way to soften the shift a little?

thanks

Mobil 1 Synthetic ATF, I am a big fan of all Mobil 1 Synthetics.