Yes, a 4 stroke is easier on fuel than an equivalent 2 stroke but in small size glo engines is isn't a big deal. Neither will run you broke on fuel. If you do go for a 4 stroke for your cub, something in a 52-60 size will be plenty(Magnum 52/OS 56). If you use a 2 stroke, a 46 will be right.(OS 46 AX) Magnum brand engines are out of production but can still be found new on Ebay or swap meets. For fuel I run 10% Omega on my 2 strokes and 15% Omega on my 4 strokes. See what your LHS sells.