They are both aluminum.

You can also use Teflon tape to wrap the threads.

One other thing to try before the oil treatment is using something like snobol or any acid toilet bowl cleaner first. Squirt some in there and let it sit for 10-15 minutes rinse it out and do it again. Dry it out and soak it with the oil, Acetone and ATF sounds good. Looking forward to trying it.