It's unlikely that you've "blown" anything.. The change from regular to synthetic does not make leaks happen. It may make an existing leak worse. I'll bet if you get under there, you will find the leak to probably be something related to your recent efforts under the car. I will pray for an early recovery. Have a great Holiday Season Jay..
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.