Sure, you could wheel your motorcycle down to the local big bike garage or your motorcycle dealer and let them charge you a few hundred baht to change your oil, but where is the fun in that? Better to spunk that hard earned money on a few litters of gasohol at your local petrol-station, no?
And if you're going to work on your motorcycle at home, a choice selection of kit will help you do the job in half the time, with half the hassle of trying to use a broom handle and the butter-wrench that came with your motorcycle's tool kit, if the motorcycle even came with a tool kit, for anything more than important than opening a fresh oil can. You can find at several downtown Bangkok automotive accessory and tool shops a range of workshop items for your tinkering delectation, which will help you do everything from change your entire suspension to simply giving the old girl a good buff on a Sunday afternoon.
Just as a word of caution, if the quality of some spanners is anything to go by, you might also want to invest in a professional packet of plasters and disinfected creams, make sure there's a fresh supply of ice packs on hand and keep the local emergency telephone on speed-dial.