As far as Foster's go, I know I'm just a dumb American, but anything that isn't pisswater and comes in an oil can for a buck at Kroger is ok with me.
Thanks for the helpful responses to those who gave them. I tightened the swing arm about a half turn with a breaker bar, the bike still wobbles. I feel like the 1/4-1/2 turn I gave to the steering head made the condition worse, but I could just be hallucinating.
Again, I don't think tire wear is an issue with new tires. The chain adjusters are both at the same notch, and the front fork caps are tight as a mofo. I think that I am going to find when I remove the steering head that the bearings are flatted, and when I remove the swing arm that the bushings are toast. Neither of these seems hard to do, but it has been so warm and delightful out that I can't stop riding with my quasi-dangerous (or completely normal, depending on who you ask) wobble.
The other issue is lack of dinero, and my wife's car is pissing oil. I think she popped the pan (not a euphemism). This weekend I shall disassemble things and check them in the hopes that I can save some cash by actually diagnosing something rather than throwing parts at it or calling it normal.