I'd reiterate the copper gasket on drain plug. If you don't have replacement , you can anneal it by putting it on an open flame. I use 20-50 motorcycle oil which tends to have zinc in it.
Castrol and even Rotella eliminated it years ago. The local race shop sells a Brad Penn semi-synthetic oil. I use it in some older motorcycles when I have gone through the engine.
Changing out the canister is a real trip. My 1st time for some reason I was expecting 4qts. of oil. Imagine my surprise......
I change my plugs over to the Centerline ones with a head for 27MM socket and magnet.
A final statement about a new engine is to run NON-Detergent in the beginning.