2X, I buy spark plugs, oil & filters from the chain stores, [Schucks Auto, I won't buy from Auto Zone since they sold my son the wrong serpentine belt & argued it was the right one], but I buy all my hard parts from Car Quest or Napa. Napa is pricey but Car Quest gives me a professional discount and has never sold me the wrong part[yet]. 90% percent of the posts concerning wrong parts & info on this forum specificly mention Auto Zone & my experiences with them have not been good. Working on your rig is enough of a challenge when you have the right parts.:soapbox: