To thin chocolate candy coating, how much oil to use? I am trying to use chocoate candy coating on chocolate transfer sheets. The normal chunk of chocolate candy coating is too thick when melted, so I used vegetable oil to thin it for better spreading.

I used 1:2.5 ratio for this, 20ml oil for 50ml chocolate. It was thin and soft enough for spreading and hardens nicely in the refridgerator. 

The problem is, however, that it stays soft and even a little bit runny at room temperature :(

I don't think this is a problem if my chocolates stay in the fridge but it will be problematic when stored outside.

Is my ratio off? Any other tricks you can suggest? Or if you have a golden ratio of your own please share!

P.S.: I used a kroger brand white chocolate candy coating

(SUGAR (SUGAR, CORN STARCH), PARTIALLY HYDROGENATED PALM KERNAL OIL, COCOA PROCESSED WITH ALKALI, CORN SYRUP SOLIDS, NONFAT DRY MILK, MILK POWDER, COCOA, SOY LECITHIN (AN EMULSIFIER), NATURAL FLAVORS.)
Yes your ratio is off. After melting if your coating is too thick add vegetable shortening (Crisco) a little at a time until you reach the desired consistency. Start with a tablespoon per pound and add just enough to get to the consistency you need. Crisco is solid at room temperature unlike veg. oil so your final product shouldn't have to stay in the fridge.