Can I put a new stereo system in a year 2000 Oldsmobile intrigue?

I am getting my license soon and I'll be driving my sisters oldsmobile intrigue since she got a used acura. Could I get a new stereo system to put in there? or is it proprietary system?|||You can put a new head unit, speakers, subs, anything at all in any automobile. It's just a matter of getting the right parts and knowing how to wire it.|||yea you will just have to figure out what fits and what doesnt.