I took out my sparkplugs to see their condition and noticed some burn marks on the ceramic part. Is that normal. Also the plug model used in my car (JDM) is DILFR6A-11 where as someone else posted images of their spark plugs on the forum which shows LZFR5BI-11 I believe its the export version. so I would like to know what is the difference other than the heat rating. Also I am not able to find either models in Pakistan hence can someone tell me an equally good alternative for these plugs.
Rgds
Kashif Rahman