I wish you could describe exactly what you meant by burnt. Because that could help with reading the plug and that in turn could give an indication of what is going on in the combustion chamber. If the thermal insulator at the center is completely melted for instance it could indicate that the mixture in the chamber is too lean and hence wearing the plug faster. If you have black deposits on the electrodes then the mix is too rich or there is oil leaking from either your rings or gaskets into the combustion chamber causing fouling and early destruction of the plugs, Mind you, I am assuming that your LFR 5As are the manufacturers recommended plugs otherwise their ratings could also affect what is going on in the combustion chamber and consequently the plugs. A rating of 11 for NGK is usually a cold plug and it will do well if the engine is frequently run at high speeds rather slow town start and stop idle situations.
The 11 refers to the plug gap which is 1.1 not the rating. the rating of the LFR5A is 5 which is a hot plug you can go up to LFR6A-11 and it will still be ok, I presume you do a lot of highway driving, because the LFR5A are mostly for city driving and short distances.The 11 refers to the plug gap which is 1.1 not the rating. the rating of the LFR5A is 5 which is a hot plug you can go up to LFR6A-11 and it will still be ok, I presume you do a lot of highway driving, because the LFR5A are mostly for city driving and short distances.
Answers & Comments
I wish you could describe exactly what you meant by burnt. Because that could help with reading the plug and that in turn could give an indication of what is going on in the combustion chamber. If the thermal insulator at the center is completely melted for instance it could indicate that the mixture in the chamber is too lean and hence wearing the plug faster. If you have black deposits on the electrodes then the mix is too rich or there is oil leaking from either your rings or gaskets into the combustion chamber causing fouling and early destruction of the plugs, Mind you, I am assuming that your LFR 5As are the manufacturers recommended plugs otherwise their ratings could also affect what is going on in the combustion chamber and consequently the plugs. A rating of 11 for NGK is usually a cold plug and it will do well if the engine is frequently run at high speeds rather slow town start and stop idle situations.
The 11 refers to the plug gap which is 1.1 not the rating. the rating of the LFR5A is 5 which is a hot plug you can go up to LFR6A-11 and it will still be ok, I presume you do a lot of highway driving, because the LFR5A are mostly for city driving and short distances.