We don't use SWIM here. Also, I'm moving this to the correct section, but it might not stay open for long. I'm sure that you will get your answer first though.
Having said that, both methadone and oxy don't really produce a rush, so there is no point in mixing the two. Furtermore, there is no real gain to IVing either of the two. Methadone doesn't produce a rush and will last much longer if you just take it orally. The same goes for oxy. For a lot of people it doesn't produce a rush when IV'd, for others it does, and I would say on average it produces a very mild rush that doesn't compare to that of dilaudid, morphine, heroin, or oxymorphone.
Support --> Other Drugs