You may ad some castor to the Model Tech Fuel. I do not know what type of engine are you using but some engines tend to run hotter than others, then some castor oil is a need for them. In my opinion using a good after run oil is really a smart choice when you know that your engine will be stored for a month or more time and it also depends on the humidity in your region or the place where your planes and engines are stored, long time a go I used to store the planes and engines in a large laundry room in home, that was a bad idea because there were a lot of humidity there, wings of some planes tend to warp and engines will start to show corrosion (even if you use Omega fuel regularly). Now I store the planes in a very dry and dark room and also use after run oil when I know that a particular engine will be stored for more than one month.
Use a fuel filter and retune your engines, Model Tech is not a bad fuel but I do prefer Omega because of the castor oil.
Good luck.