Whats that noise coming from my 318?
Sounds like a lifter to me.
If you watch the video it takes awhile for the rocker arms to start getting oil.
I personally would run a bottle of marvel mystery oil thru the engine oil and let it run for at least 15 minutes.
Then change the oil and filter
Personally I would use 15w50 mobil-1 as it is designed for flat tappet cams and that's what I've used in my 340 for over 10 years