I don't know from Bio
I can't speak to bio-diesel. Never had access to it and have never used it so far. I do have an American Tanks 40 gallon aluminum in-bed aux that has been in constant service since December of 2001. Aluminum is pretty resistant to oxidation in most any service. Mine still looks clean when I peek into the filler. It DOES scavenge fuel additives (I found this out the hard way a couple of years ago when I gelled up at 0430 in the morning in the middle of the desert at -45 degrees F.)
Tom Ashley 2004 6.0 2500HD/Silverado CC/SB/4x4