Brian,

I use synthetics in the tranny of my 95 E320, of which I don't believe is that much different than the one in your 280. I've used Amsoil synthetic ATF and Mobil 1 ATF. I prefer the Amsoil but mainly I use the Mobil 1 because I can get it easier at any Autozone.

Just make sure to drain your converter and change your filter while your at it.

Dale