For reliability it is advisable to replace the spark plugs every 10,000 km. Make sure you have the correct electrode gap, which can be measured with a feeler gauge. This fact and the tightening torque are mentioned in your workshop manual, don't think "I know" because before you know it, you twist the spark plug wire out of your cylinder head and it won't be a routine job anymore.
For each spark plug, the degree of heat is mentioned, a rule of thumb to determine which degree of heat you would need is as follows. With NGK, the higher the value, the colder the spark plug and with Bosch, the higher the value, the warmer the spark plug. You cannot compare the values with each other, NGK and Bosch have their own value system in which the heat level 5 of NGK is equal to the heat level 8 of Bosch.
Note : Check the electrode gap before installation and adjust it to Volkswagen specifications if necessary, the manufacturer's factory specification as stated does not always match.
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