When All Else Fails....
...follow instructions!
Yesterday, I took my bus downtown to a mechanic to get the valves adjusted. Knowing in advance that it would take about an hour to do the job, and that it would take about an hour to ride the city bus back down to pick it up, and that the bus had to sit for a couple of hours to let the valves cool before they could be properly adjusted, I told the mechanic to call me just before he started the job. That way, by the time I could walk out to the city bus stop, ride downtown, and walk from the bus stop to the shop, he'd be done.
So when did he call me?
After he had finished.
Another hour of my life I'll never get back.
And now I need to find another mechanic who works on VWs.