major oil leak!
 

Took my GLK to dealer for B service. When I picked it up service guy noticed some oil dripping so took it back for a look, said the oil filter seal ring had been twisted, they fixed it. Next day I drove about 100 miles and the "check oil level at next refueling" light came on. I called service guy and he said it meant oil was slightly low, just check when I stop for gas. Luckily a dealership was another 30 miles away so I just stopped there. As soon as I got out I could see oil pouring out onto the ground- at least 2 - 3 cups, who knows how much I lost on the road? I needed to pick up my daughter at the airport, so asked for a loaner while they checked it out, didn't think to check the oil level myself.
They called later to say they found that the oil seal ring was broken, they fixed it and washed the engine. I picked it up and drove back home, another 140 miles. It was still smelling of burned oil when I got home. Plan to call the dealership here tomorrow, is there anything I should check for? I don't know how low the oil got...
Thanks for any help.

Unfortunately those things happen, Ive seen it many times. Most likely its just residual oil that's burning off and there could be oil on the exhaust pipe too. Give it some time and it will go away. The o rings can twist, but usually the seal should be lubed up before screwing on the filter. Sometimes the oil filler cap doesn't get put on correctly. good luck! if the oil got really low, it can cause camshaft failure, scoring, noise, cylinder wall damage etc.