Perhaps you could have just asked "which is the safest formulation of oxycodone for IV use?" That would have made this thread easier.
In fact, I think I will change your thread title so you get more replies (it's always best to have a tile that clearly outlines your question). We can't discuss how to convince your doctor to prescribe you a specific drug or formulation though, I know you didn't seem to actually be asking that but just putting that out there. Whether or not it's a good idea to just go in and ask for a specific one with most doctors is another issue, but apparently you don't seem worried about that.
This thread borders on not really being acceptable, but personally I do think your question is acceptable since if you're going to be injecting pills it is in the interest of harm reduction for you to know which ones are going to be safest for injection.
Also I don't think it's necessary for people to question or criticize what you are doing on here, there are plenty of legit pain patients on Bluelight and plenty of people who are prescribed drugs use them in ways they aren't supposed to, whatever one's motivation is for doing so is not really anyone's place to judge here IMO, although you will likely encounter some resentment from people who feel that people abusing their meds can create difficulties for pain patients as a whole.
So the first thing I can think of is that a regular release formulation is going to be much better than an extended release (ER) formulation for injection. Many pain patients like to have an ER form and an IR ("instant" or regular release) form, so they take the ER form on a schedule and then use the IR form for breakthrough. If your main reason for injecting is to have fast strong relief from pain and withdrawals, it would be a great idea to see if you can keep your use to mostly oral - if you take your pills before your pain or WDs become too strong, it will be much easier to control. So that may be something you want to consider. BTW, most people on here seem to agree that oxycodone is not even worth injecting, that the only real benefit to injection is a faster onset and is not worth all the risks that come with injection.
Forms of IR oxycodone I am aware of:
Oxecta (made by King, which is owned by Pfizer) - contains excipients that make crushing the tablet into a powder difficult, instead causing it to break into chunks. When combined with water it forms a viscous gel making it nearly impossible to inject (at least not in a remotely safe manner). It also contains a nasal and respiratory irritant to make intranasal use unpleasant/unsafe. You obviously don't want to inject this one.
Roxicodone (made by Xanodyne) - The 5 mg Roxicodone tablets contain the inactive ingredients: microcrystalline cellulose and stearic acid. The 15 and 30 mg tablets contain the inactive ingredients: microcrystalline cellulose, sodium starch glycolate, corn starch, lactose, stearic acid, dye.
Generic oxycodone: There are many generics but here are 2 that I know of that contain the least number of inactives.
5mg, 15mg, 30mg tablets made by Mallinckrodt Pharmaceuticals - Inactive Ingredients: microcrystalline cellulose, lactose monohydrate, stearic acid (+ dye in the strengths over 5mg)
10mg, 15mg, 20mg, 30mg tablets made by Ethex - Inactive Ingredients: magnesium stearate, microcrystalline cellulose, silicon dioxide, stearic acid (+ dye in certain strengths)
Now I have no personal experience with injecting the above mentioned pills, but as far as I've heard they shouldn't gel up. Did you find the Roxies were gelling up? A micron filter is extremely important when you are injecting pills, in order to filter out as much of the inactives as possible, as even some of the inactives contained in those generics are not healthy to be injecting. Let me know if you want detailed info on the risks of injecting specific inactives.
If you were meaning some type of ER oxy then that is a whole other ballgame.