My Saturn smoked a lot and went through a lot of oil. When I brought it in for an oil change, was told the oil looked like "mayonnaise" and I need a new head gasket... very expensive. Car runs fine, no lights on... could there be another problem?

Sounds like the head gasket is leaking coolant into the engine oil (milky). You could also have a cracked head--neither prospect is good.

Test each cylinder's compression. It may help you decide if it's a head gasket problem or not. If the color of the smoke is white, it's burning coolant. If the smoke is blue, it's burning oil.