Try Motsenbocker's Lift Off
Don't know if Motsenbocker's will work on the big blue stripe but it has worked for me when Goof-Off and other solvents will not work. Motsenbocker leaves a slightly oily residue so be prepared to wash it throughly with soapy water. You may even have to wash more than once.
I've used Motsenbocker's on painted surfaces and other metal surfaces with no signs of damage. I have never used it on aluminum so try it at your own risk.
Welcome to Motsenbocker's Lift Off
Lucius and Danielle
1992 29' Excella Classic
1996 GMC Suburban C2500 7.4L
2005 Chevrolet Suburban K2500 8.1L
Got a cooped-up feeling, gotta get out of town, got those Airstream campin' blues...