I too have had my best luck/success with my OPE, keeping the gas tanks full over the long storage period. With my stored car too!
When I fill my small 2.5gal plastic gas can, I mix both Sta-MMO @ 1oz/each
Where I have had even better success is by using Sta-Bil along with MMO(both at the same doseage of 4oz/10gal). So yes, my 20 gal Firebird FORMULA V8 gets 16 oz of Sta-Bil/MMO.
My enging starting after sitting for > 6-7 months, is "FANTASTIC" in my OPE and my V8 4bbl(better than just a full tank of gas). And, with the OPE, way better than when I drained the fuel.