There was a major oil leak from the valve cover gasket on the passenger side of the Nissan XTerra 06. I have tried new gaskets but the V-6 4l engine does not seal the spark plug well and should not be replaced as they are in installed on the valve covers. 13 years dried all sealing materials, including hoses. This kit, along with an air intake kit, also from Revain, repaired the leak and restored a smooth idle. Worth buying. Hope for 10-15 years with this set. Also order 3 PCV hoses as your original hoses will most likely be fried too.