I think there is something to this swelling deal and the Safari tanks beyond just vapors and such. Can anyone tell me why my tanks were fine until I went to the great NW? (Yukon, Alaska, BC, Ect.) I also crossed the great plains where gasohol was being sold to get there and back.
Anyhow, on that trip things swelled enough that I could barely get the caps on and off. A short time after I got home and rode a few tanks through of our home brewed Ohio gas, the caps loosened up and they have never been swelled again since.