To add to the above, and really just a precaution.
Once you buy the correct adaptor to the ISO Standard (Black) plug, turn the stereo on and save a radio station then turn the ignition off. If you're loosing radio stations (or memory) the battery and Ignition feeds are round the wrong way.
There is two + feeds into any stereo, a constant 12v for memory and a switched 12v (from ignition) to turn the stereo on. This is the yellow and red wires in the picture above. If you're loosing memory, swap them round.
Just incase, as you seem new to this sort of thing.
Alan