I have an 06 double cab with a 4.0 liter, which I bought new. It was time to change the spark plugs, so I went out and got 6 Denso K20HR-U11's which were supposed to be exact OEM replacements. This morning I changed the plugs and to my astonishment I found 3 NGK LFR6C-11's in the driver's side of the engine and 3 Denso K20HR-U11's in the passenger's side. (..just like what I bought..) I haven't ever changed the plugs, and I'm the only person who has ever taken a wrench to this truck. This had to have come from the factory or the dealer before I took delivery of it new back in 2006.
First Question - Was this done for a reason? If so, should I go get 3 NGK's and put them in the driver's side of the motor?
Second Question - Is this just a screw up at the factory? If so, this sounds more like something that you would see in a GM or Chrysler, but not a Toyota. (..I sure hope Toyota isn't catching "GM Disease"..)
Has anyone else ever seen this?
Thanks for any info & Have a Great Day!