I don't think they're being made any better. I still haven't been able to get the x back into the garage to pressure test it, but I pretty much know the results. I've replaced the cap, but still there's usually some blue residue around the seams of the tank. I clean it off top it off and just keep driving it for now.

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'05 E53 3.0 6mt
'17 F30 340ix 6mt
'96 E36 328is, in progress