Spark Plugs

[korbynlehr]

When should we change our spark plugs? And is one plug really better than another, especially for a Yaris?

[Tochatihu]

Here's a how-to

http://www.yarisclubuk.com/forum/viewtopic.php?p=1117

This site seems to indicate that either a platinum or iridium plug may be OEM. Given the choice I'd go iridium even though they do cost more.

What's it say in your owner's manual?

DAS

[Thumper]

I don't know if it affects the FE or not, but I also prefer platinum plugs. Cost is more, but not that horrible.

[Maxx]

Don't forget to change the wires too. Easier than changing plugs, and they degrade over time. Just be SURE to do them one at a time (as not to get them out of order), and use some dielectric grease on the metal contact points to keep moisture out.

[Ford Man]

If the car has platinum plugs in it you shouldn't need to change the plugs until the car has 100,000 miles or more on it. I have been using platinum plugs (usually Bosch) for about the last 15 years and have never had to replace a set with less than 100,000 miles on them and most of the time they will run 110,000-150,000 miles without any drop in FE. I just took a set out of my '88 Escort a few weeks ago that had been in it for about 150,000 miles and wouldn't have changed them then except the insulator on one of them cracked and was causing a bad miss. Also in most cases wires don't need to be changed unless you have a bad wire. I'm using the best quality set of Auto Zone wires on my '88 Escort and they have a lifetime warranty and will be replaced at no charge. If you do change the plugs be sure to use anti seize on the threads. I had a plug seize up in the aluminum once and strip the threads out of the spark plug hole.