NGK Spark Plug - BP8HS-15 - 6729

'BP' indicates the thread size and type. '8' is the heat rating (higher number means hotter plug). 'HS' denotes a projected insulator tip. '15' refers to the pre-set gap, though it should always be checked and adjusted.

Replacement intervals vary significantly by engine type and manufacturer recommendation. Consult your engine's owner's manual for the specific service interval. Typically, they range from 10,000 to 30,000 miles for automotive applications, but can be shorter for performance or specialized engines.

It is strongly recommended to use the heat rating specified by the engine manufacturer. Using a plug that is too hot can cause pre-ignition and engine damage. A plug that is too cold can lead to fouling and poor performance.

This NGK BP8HS-15 has a 14mm thread diameter and a 12.7mm (1/2 inch) thread reach.

While it often comes with a factory pre-set gap, it is crucial to check and adjust the gap to your specific engine's requirements using a feeler gauge before installation.

This means the spark plug does not have built-in resistors to suppress radio frequency interference (RFI). It is suitable for applications where RFI is not a concern or is managed by other components.

Verify the spark plug is correctly gapped. Ensure it is properly seated and tightened. Check for carbon fouling or damage on the electrode and replace if necessary. Confirm compatibility with your engine.

Check if the spark plug is receiving a strong spark. Ensure the plug is clean and correctly gapped. Inspect wiring and ignition system components.

This may indicate an issue with the engine's combustion or oil control. Clean the spark plug if lightly fouled, but persistent fouling suggests an underlying engine problem requiring professional diagnosis. Ensure the correct heat range spark plug is being used.