What might cause 2011 jeep grand cherokee oil leak?

There isn't a specific condition that is particular to the 2011 Jeep Grand Cherokee when it comes to oil leaks, so You'll find the problems that affect all vehicles applicable to it as well. The typical reason You'll encounter an oil leak is going to be degraded engine gaskets almost 95% of the time. Some seal has worn out, or become brittle with age, or just wasn't manufactured well, and fails, allowing lubricant to escape. Usually You can track which one it is by a visual inspection. Beyond the gaskets, You'll also find that the oil pan itself can leak, and especially the oil pan drain plug; if someone's over-torqued it (and we all get a bit overzealous here) then it'll strip the hole, allowing a slow drip and the tell-tale pool of black under Your engine.