Changing the spark plugs?

Just bought a 2005 Prius with 89000 Miles on the clock.......should I change/inspect the spark plugs guys?

 

Nutzaboutbolts has a youtube on 3rd gen plug removal. It's a must watch for 3rd gen'rs, what with the insane amount of disassembly needed. Anyway:

He's just pulling them for inspection, this is around 60K miles I believe. He applies anti-seize (a little too liberally in my opinion) to the threads, before reinstall. He claims to be an ex Toyota mechanic.

I'm on the fence regarding this. I took a look at our plugs a while back, used a slight amount of anti-seize.

 

never hurts to pull them, so they'll be less resistant at 120k. and a fun time is guaranteed with a cooler of ice cold beer and a few friends to kibbutz with.

 

Welcome to PC from a fellow Britt.
If the 60,000 mile service was carried out by Toyota "see your service book or go on line to check service history" they will have removed the plugs for inspection and refitted or replaced them. They usually replace them "more profit for the same work", but the manual says they are good to 120,000 miles. Many here have gone past that figure without problems, and after removing the plugs have found them to be still serviceable.

John (Britprius)

 

I just replaced my plugs at 180,000 miles. I don't know if they were pulled at 60k, but they were still firing okay at 180. I figured I'd do the plugs as preventative maintenance at this point. I wish I'd read this thread about the anti-seize. It's only the second set of plugs I put in and the first time I've ever used anti-seize. Is there any reason that over-application (besides over-torquing the plugs) would be an issue? I did it by feel on the ratchet.
It's actually a really simple job. If I weren't doing it in the dark after a long day it'd only have taken 30-40 minutes.
Oh, I got OEM plugs from Toyota because I was getting Toytoa ATS fluid for the transaxle fluid change. At the same time I got a new OEM PCV valve... tomorrow's project.

 

One concern is that the anti-seize lube may get on the electrodes and cause misfiring. If that is not a problem for you then don't worry.

 

NGK bulletin says don't use anti-sieze lubricant.
Denso, says you can: "If threads are lubricated, the torque value should be reduced by approximately 1/2 to avoid over-tightening." LINK
Bentley manual says (page 5-17): "Lightly coat spark plug threads with anti-seize compound."
Don't have Chilton or Haynes manuals, so don't know what they say anything regarding this.

I am of the opinion that manufactures say NO lubricant b/c its subjective, and want to avoid lawsuits. How do you measure lightly coat? What does lightly coat look like? Do you apply a light coat to 100% of the threads, just the middle section of the threads (say 5, 10, or 15mm worth of threads), or the middle section going to the crush washer? Also, people have pointed out, anti-seize might possibly contaminate the spark plug tip/gap during installation, depending on where and how much of the lubricant was applied. Dry threads, tightened to a specified torque value, no ambiguity; only variable is the accuracy of the torque wrench used (if used, as some tighten by hand).

But, the fact that Denso says if you use lubricant, adjust the torque by upto 1/2, implies lubricant is OK. Denso is acknowledging what people are doing in the real world, and still protecting themselves by saying to decrease torque value. Many people here, who have a lot of automotive work experience (professionally or DIY), have had no issues with anti-seize lubricant.

NGK, is avoiding all lawsuits by saying NO. Bentley is open to lawsuits. Denso, semi-open to lawsuits. But, how many of us average folks, have the resources (ca$h) to take on Denso/Bentley, if our spark plug should snap off in the cylinder during installation or removal, due to lubricant use?

 

The plugs when new are coated with an anti sieze coating so they say do not use lubricant. Toyota say inspect the plugs at 60,000 miles and when refitting use an anti sieze compound so that the plugs will not sieze in for removal at 120,000 miles.

John (Britprius)

 

Just keeping the same wording of Denso. When Denso says lubricant, I'm sure they must have meant anti-seize lubricant. But strangely, I have read of people using a drop of two of a liquid lubricant (ie motor oil). Go figure.

Anti-seize lubricant controversy on spark plug and wheel lug nutswill never go away.

 

I don't think there's any adverse effect in using anti seize, just that you can over torque the plugs if not careful. The anti seize acts like a lubricant and if not careful, you can really torque those down unknowingly. That's the reason NGK doesn't recommend using it.