Hello everyone, I bought a 2005 Volvo S40 T5 a few months ago and the 60k mile service is coming up soon. I looked in the back of the service manual and noticed it says the spark plugs would be replaced during the service, is this necessary at 60k miles? I thought you wouldn't do this until about 90k. Thanks in advance for your help. AC

 

did mine at about 82k, service engine light came on....

 

The idea with setting service intervals is to swap out wear items before they fail. Hopefully, by following recommended service intervals, the car will always perform as intended. Obviously, there are some services that can be postponed and some that only a profoundly challenged person would ignore. Modern transverse V motors typically cost an arm and a leg to do the back plugs; the intake manifold has to come off. A simple task like changing plugs blooms into a 4 hour job!! So...they are often postponed w/ little ill effect other than slightly less power and fuel economy. Eventually, they will misfire and set a code. Timing belts should be changed on time scrupulously; failure can result in a toasted motor.
Here's some platinum spark plugs that were finally changed at 100k. Notice the missing electrode...