Lets say you do switch to something else, what will you do when you no longer get euphoria from that? You are not going to be able to get high everyday off of your meds. If you want to continue to have "fun" with them, then you should lower your daily dosage, and then save up the extras to have fun once a week. If you try to do anything more than that, it won't lead to anywhere good. You will just end up running out early, and the pain from withdrawal along with your chronic pain will really suck.
There is a cross tolerance between opiates, so if you are no longer getting euphoria from oxycodone, then you won't be getting euphoria from the equivalent dose of any other opiate. Even if you do get euphoria after switching to another med, it will be short lived, and you will be trying to figure out what your next move is to find yet another medication change to experience more euphoria.
I have seen chronic pain patients chasing the high that they once got from their meds, and it never ends well. Even if they got the dose raised, or another med added to their treatment, they ended up right back where they were before, trying to get something else to help. As your tolerance goes higher, your withdrawals will get worse, and start faster and faster after your last dose.
If you are taking 20 pills at a time without getting euphoria, it's time to take a tolerance break. It's also important to be doing a cold water extraction if the pills have APAP (acetaminophen) in them, otherwise you are doing a number on your liver.