Since not everything is made equal, what do you all think about putting in sparkplugs from different batches?

Anyone know what the 4 digit code stands for on the side of the NGK platinums plugs? A date stamp or lot# perhaps? If date stamp, how do you read it?

Also, some are made in Japan, and some are assembled in the usa, which ones are the newer ones?

 

What code are you referring to?

Like BKR5E-11? It's not a date it's a part #, and as long as the P/N is the same, and they're all brand new, it will work fine.

Look on NGK's website and learn something. 11 is the gap, 5 is the heat ranfe, B is the mat'l code. The others you will need to find on your own ...

 

I know the P/N. I was referring to these digits "M64L" "M3Y1", printed on the side of the plug, on the metal part right after the ceramic.