Hello. This is Dr. Love and I have different information than the other expert.
While it could be said that oxycodone is detectable for 48 hours for many people, it would be incorrect to say that it is never detectable for more than 48 hours.
For reference, you can review the detection times stated by the Mayo Lab, which says that oxycodone can be detected for up to 3 days. See www.mayomedicallaboratories.com/test-info/drug-book/viewall.html.
It is true that drinking water can help somewhat, but there is no clinical evidence that drinking water will limit the period of detection to 48 hours. If the other expert wants to repeat that it can be detected for no more than 48 hours, I would be interested in seeing the clinical evidence to support that statement.
Relying too much on hydration to pass a drug test will also run the risk of failing because of urine that is too dilute. Drinking Gatorade may help some of the effect on the specific gravity as an indication of the degree of dilution, but it will not help to offset the decrease in creatinine levels that is another test used to assess the degree of dilution of the urine.
I would also note, though, that the period of detection assumes that you are testing for it. The standard urine drug screen for opiates will frequently miss oxycodone because the urine drug screen for opiates is designed to detect morphine and the drugs that are metabolized into morphine, such as codeine and heroin. The semi-synthetic opiates, such as oxycodone or hydrocodone are frequently missed by the urine drug screen for opiates.
If I can provide any additional information, please let me know.