We just got this van, seems ok. Clean interior, 150k 3.8l I can tell the radiators been replaced and CV shafts. I did the coil pack plugs and wires. Runs smooth, Handel's great.

Are there any common problems with these things that I need to keep an eye on? It's main purpose will be kid delivery system, it will spend a lot of time idling in car line. We live in South Florida and yes it gets hot here.
I want to change the oil and go with synthetic. Are there any recommendations of what I need to do to keep this thing reliable?