I recently returned from spending 3 years in Italy where I purchased and mod-restored a 72 Fiat 500L, giving it a 652cc found in Fiat 126s, a brand new transmission, upgraded suspension, etc, and Abarth decals to make it resemble the famous high performance Abarth 695SS. It got to New Orleans where I had to pick it up and drive it to its new home in Pensacola. It made it to the Mississippi/Alabama border and it died. I did a few checks to see it was the head gasket like Fiats are known for. It's fine. I finally discovered oil coming out of the exhaust pipe, unburned. That tells me piston rings. I understand a car being in shipment doesn't do much for a while and needs a little time to break back in, and I thought I had provided it that. Also, I never gave any thought to the difference in gasoline between Europe and the USA. Euro gas has a decent amount more octane than American, and I wonder if that lack of explosiveness in the chamber caused this? All my fluid levels were good, serviced with the correct fluid types (15W-40) prescribed by Fiat. I can't think of why, after having driven the little car as a daily driver for about a year over there, it dies on me within the first 2 hours over here? Thank you for your time.