There are Shell and Caltex fuel depots close to me...I think they mainly supply the trucking industry but both of them have methanol in stock all the time. Shell aviation would be unlikely to have it though. Try asking at a Go Kart shop or a speed shop that deals with drag racers, they might be able to put you on to a supplier.

The Mobil Jet Oil 2 works very well but they've now got a third generation variant that won't mix with methanol. It's got a heavy brown dye in it that can stain but BP 2380 turbine oil is supposed to be clear (I haven't seen it but I know of some who use it). There wouldn't be anything on their web sites about mixing with methanol because it's only made for use in gas turbines. However, it's the only synthetic I know of that's got a higher flash point than castor and because it also lubes the gear boxes it's an extreme pressure oil.