Before you begin
Replace the spark plugs in your Volvo 240 every 60,000 to keep it running in tip-top shape. Though there were a number of engine choices for the Volvo 240, the procedure below is applicable to all SOHC inline-4 engines. There are many aftermarket companies who manufacture spark plugs that promise to increase performance and fuel economy. However, the most reliable and longest-lasting plugs are usually OEM plugs from the car's manufacturer.