well...since it seems like you care. the only things to help you along to be a good bonneville owner....
Flush out the dexcool and refill with prestone dex compatible or long life, dexcool is basically acid, it is pure evil. (wouldn't hurt to get it out of your grand am either)
After that watch your coolant level like a hawk and be sure to be concious of any large changes in fluid level
maintain your transmission, have it flushed at the recommended interval
for oil i recommend synthetic, something like mobil 1 or pennzoil platinum are good
other than that, keep her tuned up and the bonne should treat you well!