Just replaced some weeping valve cover gaskets and spark plugs on my 2004 Nissan Quest VQ35DE. Oil used has been mostly Pennzoil Platinum 5W-30 or 0W-40 lately with occasional OCIs of Mobil 1 0W-40. I probably have used Castrol or Valvoline a couple times. Manual recommends 3,750 severe service OCI, but I usually ran it around 5K miles or so depending on weather and my availability to change it. Lots of short trips to the elementary school/grocery store (one or two miles each way) with a highway run usually once a week.
I was pleased to see how clean the intake valves were. Fuel used is/was usually the least expensive lowest octane available (Maverick or Smiths/Kroger typically). No idea if either is Tier One. Have rarely used any fuel injection cleaners and have replaced one injector in the van's 162K miles. I bought it about 8 years ago with 73K on the odo.
I was pleased to see how clean the intake valves were. Fuel used is/was usually the least expensive lowest octane available (Maverick or Smiths/Kroger typically). No idea if either is Tier One. Have rarely used any fuel injection cleaners and have replaced one injector in the van's 162K miles. I bought it about 8 years ago with 73K on the odo.