See Figures 1 and 2
In order to extract the full measure of performance and economy from your engine it is essential that it is properly tuned at regular intervals. A regular tune-up will keep your truck'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 every 30,000 miles. This interval should be halved if the vehicle is operated under severe conditions such as prolonged idling, start-and-stop driving, or if starting or running problems are 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. All of the applicable steps of a tune-up should be followed in order, as the result is a cumulative one.
If the specifications on the underhood tune-up sticker in the engine compartment 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.