Hyundai Repair: 2002 Hyundai Elantra oil leak, valve cover gasket, hyundai elantra

Question
QUESTION: I bought my daughter-in-law a 2002 Hyundai Elantra. The salesman assured me it would be reliable for her. She hadn't owned it a month when the problems started. The check engine light came on and we could occasionally smell hot oil. It had a manifold problem which was covered under a recall. But it also needed a head gasket and water pump and while they were repairing that I had them to change the timing belt.  The dearlership agreed to split the cost of the repair. She drove it to college which is about 400 miles round trip and the oil light came on. I thought they just had not put enough oil back in it. I put some oil in and took it back to them, they found a very small leak at the oil pan so they took it off and cleaned it and resealed it. I kept an eye on the oil. I just checked it on Jan. 10, 2010. It was a little low but when she drove the 400 miles round trip and I checked it again no oil registered on the dip stick but the oil light has not come on. It shows no signs of a leak on the ground. I'm wondering what is going on with this car? She has been able to drive this car much since she's had it. I don't think the mechanics at this dealership are trained very well and they seem to get very annoyed when I call them. Thanks for any help with this problem.

Could something possibily happened when the mechanics put the new head gasket, water pump, timing belt and valve cover gasket on? The oil leak didn't seem to be a problem until after all this work on the car.
Sorry for repeating the original question.

Answer
That's a possibility.  The head gasket not only seals the oil from leaking out of the engine (like most other engine gaskets and seals), but it also keeps the oil separate from the coolant.  If it somehow was not installed properly or was damaged during installation, it could allow the oil to leak into the coolant or out of the engine.

While I realize you have little faith in the dealer, you do have some incentive to continue to take the car there.  Since you purchased it from them, they're in a position to be leveraged for assistance in repairing your car.  In this case, they're potentially responsible for fixing the leak, since they could have created it.  

Having the oil leak issue checked by a different reputable and competent shop (dealer or not) is also a good idea.  This helps you insure that the dealer is not lying to you to avoid repairing the car.  If the other shop finds the problem, ask if they'll show it to you.  This way you will have seen it and can use that to pressure the dealer.  Additionally, you'll know what to check (if it's possible for you to do it yourself) after future repair attempts.