In order to extract the full measure of performance and economy from your engine, it is essential that it be properly tuned at regular intervals. A regular tune-up will keep your car's engine running smoothly and will prevent the annoying breakdowns and poor performance associated with an untuned engine.
A complete tune-up should be performed at least every 12,000 miles (19,200 km) or 12 months, whichever comes first. The interval should be halved if the vehicle is operated under severe conditions such as trailer towing, prolonged idling, start-and-stop driving, or if a driveability problem such as hard starting or poor running is noticed. It is assumed that the routine maintenance described in Routine Maintenance has been kept up, as this will have a decided effect on the results of a tune-up.
If the specifications on the underhood tune-up sticker (located in the engine compartment of your car) disagree with the tune-up specifications chart in this section, the figures on the sticker must be used. The sticker often reflects changes made during the production run or revised information that applies to the particular systems in that vehicle.