When getting oil changed, mechanic showed water in oil. This is a 1998 Grand Prix SE with 111,000 miles..Is this serious enough to trade, and could it more likely be from intake or blown head gasket?? Help...

Water in the oil is a bad thing...depending on the amount and how long it has been in there determines weather or not there has been sufficent damage to consider getting rid of the vehicle.

Intake would be one of the first places I would look as the source of the leak.

Water in the oil is a bad thing...depending on the amount and how long it has been in there determines weather or not there has been sufficent damage to consider getting rid of the vehicle.

Intake would be one of the first places I would look as the source of the leak.

If it is recent and the car is in good shape and the problem is because of the head gasket get quotes to see how much is to replace it.
Then decide what is more cost effective for you, replacing the head gasket or getting other car.

So you have the 3100 or the 3800 motor in your SE? If it's the 3100, then the best place to start looking for the problem would be the intake gaskets...as GMMerlin pointed out. That engine seems to have a history of intake gasket problems.