Curious how that might cause any issues? Before longer trips I WAY overfill my tank, until the fuel is just about level with the fill. It is amazing how much more fuel/miles you can squeeze into that tank! Most times I plan to leave the next morning, and have about an 8 mile drive from pump to house, so some fuel is burned but not much. I know you are probably headed for the whole 'expansion' thing but I've never run into issues so far, with the 4R or my last SUV doing this. I do park in a garage, not heated, but stays around 50 in the winter. This is not something I do on a regular basis, maybe 6 times a year or so.