score:4
You know better than most of us that Chinese visa rules change by the day, place and mood of the officer, but yes, I found several reports on the webs that visa extensions were successfully done in Xining previously.
(And you should apply at least seven days beforehand and have proof of your financial means as part of your paperwork):
Caravanistan forum (in 2014), see also their visa extensions section at the bottom of their Chinese visa page:
Later I got a 30 days extension while I was in Xining, Qinghai province. The visa extension is in fact a kind of new visa and the 30 days extension will NOT be added to your current visa. So apply for extension 7 days before your current visa expires. Less than 7 days before your visa runs out might be a problem.
For the 30 days extension needed to submit:
- written planned travel intinery (just places, no hotel bookings required)
- proof of finance for each day 100 USD, so total 3000 USD. They don't want to see cash. Simple print out of your online bank account was fine.
- 160 RMB fee
This was processed in 3 working days.
Travelchinaguide forum, (2013, not sure whether pursued/successful)
As to the regualtion, you should submit your application for extension at least a week before it expires. So, it means the extension takes 5 working days. It is not enough if you only stay in Xining for 3 days only. I try to check online, and got this address: No. 35, North Street, Xining, Qinghai Tel: 0971-8251758
Lonely Planet forum (2013)
Somewhat of a longer thread so summarizing here. Visa extensions seem to be no problem there, alternatively people suggest Lanzhou where apparently the PSB used to be fairly lax in the past. Have your documentation at hand (photos, hostel confirmation, passport, proof of funds, ...)
Warm Showers forum (2013)
In Xining we need to provide financial evidence, as well as the hotel registration, form, photo etc. They'd only give us 25 days because we arrived 5 days before the visa was due to expire and they wanted us to apply 7 days beforehand. They also started the extension from the day of application not the day of our visa expiry. (Feb 2013)
Unfortunately I was not able to find any accounts more recent than 2014.