1998 Nissan Sentra Burns Oil

My daughter’s 1998 Nissan Sentra goes through about a quart of oil every 400 to 500 miles. I have checked underneath the car and there are no major leaks there. It has a few drips on the oil pan, but not enough to account for that much oil loss. What is the possible cause of this loss? What is the best way to fix or slow down the loss?

Here’s what I would do if this were my vehicle and had this problem.

First, try adding a half a can of SeaFoam to the engine oil. If the piston rings are stuck because of gum and varnish, the stoddard solvent in the SeaFoam may free them up. If after a thousand miles it shows no improvement, then the next thing to try is adding a can of RESTORE for 4 cylinders to the oil. This fills in the scratches in the cylinder walls that results in oil burning.