Hi Skater,
Welcome to the forums.
You are relatively new to the whole pain management thing so let me see if I can explain things so that it all becomes a bit clearer for you and easier to understand.
Tolerance is something that happens to most patients , slowly, over time after being on the same meds and doses for an extended period of time. It doesn't happen overnight or normally in a short time frame of being on any particular medication.
You were on hydrocodone ( vicoden, norco) for awhile and it is perfectly normal that after some months, and years, they tend to start working less well than they did in the beginning. This is because your body becomes "tolerant" to the meds. Hydrocodone, oxycodone, and others are what are commonly referred to as "short acting" opiates. This simply means that they are meant to release the dosage within a short time frame, all at once and then slowly over 4-6 hours, the blood plasma levels of the opiates/medications slowly recedes.
Oxycontin is what is called one of the long acting versions of oxycodone. There is no tylenol in the long acting versions, however, they release the medication into your blood stream over the course of 12 hours, so instead of taking a pill every 4-6 hours, you are only taking two tablets a day. However, only take them whole since the release of all of the medication at once can be lethal. Do not alter the delivery in any way. Take whole tablets only. Do not cut, crush or ingest them any other way. They are meant to be broken down in your digestive system over the time frame of 12 hours or so.
The difference between the long acting and short acting versions of these medications is that the release of the medication ( long acting version) is done slowly, so that you develop a steady blood plasma level in your blood stream. Many people new to this type of medication think it is not working because they don't "feel" the onset of the medication as some do with the short acting versions. This is not the case. It can however take a couple of days for your body to develop the proper blood plasma level, this is not unusual, so don't think that it isn't working just yet. It may take you several days to determine, what level of pain relief you are getting from them. The other thing is that you are taking the lowest dose of oxycontin that is made in the long acting version- so after a couple of weeks, if you still are having more pain than you can deal with ( most pm doctors want the patients pain level to be reduced by about 50% of what it was prior to using pain meds), then it may be time to talk to your doctor about his ideas and recommendations. Do not ever take more of any medication prescribed by your doctor, without his permission and direction, nor should you take it more often. I know that it can be difficult waiting this out, but when switching to a new medication, the doctors tend to start lower doses to see how the patient tolerates the new medication and to make sure that there isn't any problem with nasty side effects or over sedation. Then if necessary, dosages may need adjustments, but not always. Once you have a steady blood plasma level built up, you may find that the oxycontin works just fine for you.