We haven't yet. I started on it, but the task keeps getting bumped by more fun and/or paying activities.
That said, I had planned to get back at it this coming week.
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FYI, I'll probably fill the U.F.O. one last time this year, either late this month or sometime in November. This tank is currently sitting at 97.x MPG (US), says the factory gauge (it has been close more often than not).