Jim, I mix it approximately 15 to 1 (2 oz per quart or litre).
I think 20 to 1 will also be fine.
These mixtures are a little rich on the oil and I consider this cheap insurance.
I would recommend against a fuel system cleaner.
Firstly, there is nothing to clean in a brand new engine.
Secondly, these are not good lubricants at all.
Gil