The DLE engines are low compression engines and designed for (87 octane!!), personally I use a 22x10 prop and use a 50 to 1 oil mixed at 40 to 1 on 87 octane only, what I mean is every 2 stroke oil has a designed ratio (ie) 100 to 1/ 50 to 1 / 32 to 1 etc, make sure you're not taking an oil designed for a 100 to 1 ratio and mixing it at lets say 32 to 1 thats a no no, I'm a big fan of being a tad heavy on oil thats why I use an oil designed for a 50 to 1 mix and run a 40 to 1 mixture or a 100 to 1 oil mixed at 80 to 1.
Get to heavy of a mix on the oil and you will have a bear of a time getting it started as you will have had some low rpm engine time on it before shutdown the last time you used it which will have loaded up the base of the motor with oil that did not burn completely.
When you do get it started again does it puke out some black goo on the bottom of the plane after the first flight of the Day? if so what I'm saying might be worth investigating as I kinda had the same problem in that I tried some new synthetic oil and mixed it at 40 to 1 like usual, come to find out it was designed to be mixed at 100 to 1, we about wore out the needles figuring that one out.