getting ready to change plugs and realized I ordered/recieved RN12YC not RN11YC.
are they ok to use or do I need to get RN11YC?
1998 Disco 1 4.0

 

They are OK to use. For Champion 12 is one step hotter than 11. So, especially if most driving is short trips or low speed, 12 is probably better. For long trips or high speed, 11 may be better, but you probably will not notice any difference. If the old plugs tended to turn black, 12 will be the better choice.

 

thanks Johnzo - I tried finding the difference but wow is that a rabit hole..... and no one locally or rockauto stocks the 11's......

 

Let us know how it works out.

I like trying various spark plugs. My favorite so far is NGK V-Power BPR6EY, nickel tipped, copper core with a V notch on the center electrode. I also like the NGK G-Power or Bosch fine wire platinum center electrode. Great performance without breaking the bank. With the wasted spark system on the 4.0 L, I prefer a double platinum plug. For example, Autolite APP64 or 65. Iridium plugs cost too much, unless you never want to change them again and plan to drive more than 120,000 miles.

 

The Champion RN11YC4 cross references to the Champion 322S. I picked up a 24 pack of the Champion Copper Plus 322S on Amazon for $49.