Replacing catalytic converter

I am attaching the process on how to replace this. I would not replace it with pipe adapters from the parts store. You need proper placement of the converters but you can get just the converters so you don't need to replace pipes or sensors.

However, if you have oil going through the exhaust we need to figure out why or you are just going to clog the new converter as well.

So I would start with a compression check. Here is a guide that will help with that:

https://www.2carpros.com/articles/how-to-test-engine-compression

If you have ring issues that will allow more oil into the combustion chamber and through the exhaust. The other possible cause is a PCV valve that is clogged. I attached the testing and replacement of the PCV if that turns out to be the issue.

Let us know what questions you have.