Most of the better engine manufacturers use some type of sealant at the case halves. Once they heat up gas under pressure has been known to leak with any of them, especially where cases were altered to make them thinner, aka lighter. So hopefully DL does use a sealer. It doesn't take much, but that tiny bit can be the difference between a good engine and a bad one.

None of the model airplane engine manufacturers are makiing ultra high tolerane products, nor are they selling a new engine for $4,000.oo to $7,000.00 like the auto manufacturers so a little sealant should not be an issue.