Newly purchased 2006 Porsche 997 Carrera 3.6 stopped by for us to perform quick multi-point inspection and review the maintenance records. With 45,000 miles miles on the odometer, spark plugs & manual transmission fluid were the only services that were needed. Porsche recommends having spark plugs replaced every 40,000 miles for naturally aspirated models. Replacing them at their scheduled interval will ensure consistent production of optimal combustion, better fuel economy, and less harmful emissions.