Where is the oil gasket adapter located?

Hello, are you saying you have oil in your coolant system? There is a Transmission Cooler line that runs through the Radiator. The transmission fluid will have more of a reddish look to it.

Here is a guide that will help with finding if a head gasket is blown.

https://www.2carpros.com/articles/head-gasket-blown-test

However, are you suspecting that the oil filter adaptor housing is the issue? If so, I attached the process below on how to replace it so please run through this info and let us know what questions you have.

Thanks