Synthetic Oil - good or bad?

synthetic is costly if you run a deep pan and have many vehicles.I was using Amzoil for awhile and went back to Penzoil 5W30 in everything even my new Toyota. I too run vehicles to 300K and never had any problems.
I can hear all the gasps and murmurs!
If i do a change on my plymouth with a milodon pan, my camaro, and my two diesels,......there goes 40 quarts.