How far have you gone on a set of plugs?

I've seen a couple of threads today mentioning changing spark plugs and I'm wondering how many people have run plugs forever and/or run them until they had some kind of failure.

I sold auto parts for Napa and O'Reilly as well as working at three GM dealerships selling to the shop mechanics. I began to wonder about maintenance and recommendations and started to test them using my own cars. At one time I was commuting a hundred miles a day, so racked up some miles.

I had a Jeep Cherokee that I bought with 40K on it and suspect it had original plugs in it, and I never did any drivetrain work on it other than changing the engine oil and filter as recommended in the manual, and maybe a couple of air filters. I sold it running fine with close to 200K on it.

I haven't changed a plug in any vehicle I've owned since eletronic ignitions became common, although I've pulled a few to look at them and see how they look.

Just wondering. I've just never been one to break cars like some people do.

Edit: I have a theory... and I'm just testing it because I have the curiosity, time, and financial resources to do it. I've seen people changing their oil too often, changing belts, and doing other maintenance because "it's cheap insurance" for as long as I've been working in the business. And yet it seems like the people that do the most maintenance have the most problems with their vehicles. That seems counter-intuitive, but nevertheless that's what I have observed. So curiosity...

 

So no one has ever tried to run their plugs for longer than recommended changes?

Then how do you know they need replacing?

 

Haha my last truck ('99 2.7L prerunner) I ran the same set of plugs for well over 150k.

 

I'll run 30 Kmiles in my truck.
Our '02 TrailBlazer had 113K on original plugs.....I was very neglectful on that ride....... I let too many things slide. Fortunately, that 4.3 Vortec Inline 6 is a bomb proof.

 

With modern EFI, engine tolerances, and plug quality, they don’t really have the issues like the old days. 100k or so is standard, and that’s probably just a WAG anyway

 

I stayed around the 100k range in past vehicles but will change at 60K on my taco when I get there

Usually change my lawn mower about every 7-ish years

 

Bought my current 2012 tacoma with 150k and replaced the spark plugs at 155k. Pretty sure they were the original plugs since each side had different brand plugs.

 

I bought a 4.3 truck that had never had the oil changed. Collapsed lifters and rattled like a tin can full of rocks. But as you say, bomb proof. Several oil changes with a quart of transmission fluid and the engine quieted and I sold the truck many miles later running fine.

 

Is that really standard on Taco's? Different plugs on either side? I've heard it before but it sounds so weird. Gotta wonder if there is a reason...

 

Same here. Bought my 2005 with 168k plugs and I changed them right away. They were definitely OEM because of the two different brands and they looked absolutely atrocious.


I wouldn't recommend it though. I don't see the point of willfully neglecting your truck when plugs are so cheap.

 

From what I've googled and found on this site, yes. Here are mine.

 

So was the truck running good when you replaced them? What did the plugs look like when you removed them? Gunk? Or noticable wear? Did you replace them with the same two brands on each side?

 

Those plugs look great for 150K miles. Clean and no noticable wear from what I can see. I wonder if different plugs on each side is something that should be continued?

 

The mixed plugs is likely a decision by Toyota supply chain. Multiple suppliers help secure the best cost and a continuous supply.

 

It was running, but I wouldn't call it great. I did a bunch of maintenance at once so I can't say if any one thing had an appreciable difference. I cleaned the MAF, throttle body, changed plugs, etc. After I did all that it was running better. I didn't do the two different brands, I just picked one and stuck with it. I believe Denso. You can get OEM plugs from a dealer for less than $3 each which is what I do every change.

 

Yeah, it would be very interesting to drive the truck after each, individual, maintenance. I'd probably have used the old plugs unless the truck swas still running badly after all the other services, just to see what happens.

 

I replaced them on a Ford Escape at 155k only because the valve-cover gasket failed and flooded the plugs with oil. Otherwise they were probably fine.

That being said....it's a relatively simply and cheap job. Not a big deal to swap them at the prescribed intervals.

 

That is true. My '06 4L uses the basic copper Denso. I purchased from the local Toyota dealer, <$25 with tax for the set. I spent less than 1 hour doing the change.

So, $25 and 1 hour of time every 30K miles.....isn't a big deal.

 

The 40K mile sparkplug change in the manual seems crazy, but there must be a reason for it. The 4 cylinder had a more standard 100 or 120k change I believe. I changed mine a little after 40K, and I feel a little bad for not doing it before now. I'm at almost 108k, so a bit overdue. They didn't look bad by any means at 40k. Some of those pics above show a LOT of the electrode worn down, leaving a pretty big gap. I dont really know what this does, but either way I still plan to swap them soon.

 

I have a theory... and I'm just testing it because I have the curiosity, time, and financial resources to do it. I've seen people changing their oil too often, changing belts, and doing other maintenance because "it's cheap insurance" for as long as I've been working in the business. And yet it seems like the people that do the most maintenance have the most problems with their vehicles. That seems counter-intuitive, but nevertheless that's what I have observed. So curiosity...