Oil in my radiator?

Hello,

The most common cause of oil and coolant mixing is a bad head gasket. When you have a bad head gasket there will be oil in coolant and coolant in oil.
Best way to find out if you have a blown head gasket is to do a test.

Here is a helpful guide on the test:

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

When you have a blown head gasket, there is usually white smoke out of the tailpipes.

https://www.2carpros.com/articles/white-smoke-or-steam-coming-from-the-exhaust-pipe

I have attached diagrams for your reference.

Please let me know of any questions.
Thank you.