Hi Yankee, Living in the North East in New Hampshire (The Granite State) the winters here are very harsh. The road salt and brine spray that is applied during snow removal certainly takes it toll forming rust that eats cars from the outside in. However, that oil tube section where it originally broke was right behind the exhaust manifold where it was severly blistered and weakend which made me believe that the extense heat in that area contributed to some degree of metal fatigue and failure when I tried to flex it taking the manifold out.
The heat might have had a little to do with it, but the majority was the crap they throw on the roads up there (no stranger to it - spent most of my life in NY). My dipstick tube is right next to my turbo manifold and I've never had an issue.