If it has been sitting for 5 months with no fuel or oil in it then its probably dry, actually I know it is. So turning it over is not a good idea. Put a small amount of fuel in it and compression will come back.

What happens is the fuel evaporates and all that is left is the oil, the oil will then start to dry out.

If they have been sitting you want to get a little raw fuel in them to turn it over....If you run it, it should come back just like before. Its common when then get dry to have the compression feel like nearly nothing is there. The ring could be hung up in the goop left from the oil that was in there.

I can't comment about the fuel, I have not run it. If you are looking to change check out the Cool Power 30% heli blend it is about the best on the market today. I run that in my engines.

Troy Newman
Team YS