# maintenance interval questions (spark plug and tire rotations)



## jblackburn (Apr 14, 2012)

Iridium spark plugs should probably be changed every 60K in a Cruze. Gapping/maintenance is more frequent on the forum-recommended NGK BKR-series plugs if you chose to run those.

Tires should be rotated every 5000-7500 mi.


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## blackbird (Nov 6, 2017)

If you don't rotate tires and the car maintains a very good alignment you'll still likely get some odd wear patterns over time, but if it's something like the Cruze which isn't a sporting car with aggressive camber and toe settings they may last a long time. You'll still get the longest service life and even wear, which provides the best traction if you rotate as suggested.

For cars that run platinum and iridium long-life spark plugs, the metal (strap) for the ground electrode is still subject to a lot of heat cycling. As such the gap may increase slightly over time but if you try to re-gap the plug it will further weaken the metal and the gap will likely start to grow apart much faster. Back multiple decades ago people would also take a wire brush and "clean" the center and ground electrodes but that isn't normally recommended on newer plug designs. For the cost and how long they can be run it's normally best to change them.

Because of the longer service life and the dissimilar metals (steel plug body and threads going into an aluminum head) make sure if you change them to use a very light coating of high temperature nickel anti-seize on the threads and dielectric grease inside the boots/connectors to reduce moisture and other contaminants getting in over time.


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## Merc6 (Jun 8, 2013)

I was under the interpretation "shiny threads" do not get anti seized as it changes the heat ratings and the torque numbers if you actually used a torque wrench with the intent of not stripping the aluminum heads. 



> 1. Anti-seize
> NGK spark plugs feature what is known as trivalent plating. This silver-or-chrome colored finish on the threads is designed to provide corrosion resistance against moisture and chemicals. The coating also acts as a release agent during spark plug removal. NGK spark plugs are installed at the factory dry, without the use of anti-seize. NGK tech support has received a number of tech calls from installers who have over-tightened spark plugs because of the use of anti-seize. Anti-seize compound can act as a lubricant altering torque values up to 20 percent, increasing the risk of spark plug thread breakage.
> 
> https://www.ngksparkplugs.com/about-ngk/spark-plug-101/5-things-you-should-know-about-spark-plugs


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## blackbird (Nov 6, 2017)

The coatings helps but I've still seen problems where people run OEM plugs 100k miles or more in certain environments and have problems with galling. The anti-seize does affect torque but seems to provide slightly better protection. My personal preference, if you're religiously changing plugs at shorter 30-60k mile intervals a factory coated/plated plug is likely fine, but if there's a chance the plugs might get run longer or if you live in a moist climate or have severe winters and a lot of corrosion build up I'd still consider using it.

It's also good to check if the factory service manual torque specs call for dry or with anti-seize. If it shows anti-seize than the torque spec likely already accounts for that. I suspect a lot of people don't bother with a torque wrench, and in that case remember nearly all modern aluminum headed engines only need the plugs just past snug.


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## ProDigit (Aug 31, 2015)

I checked the tire tread, and the front tires both have slightly more wear on the outside than on the inside.
I do travel mostly alone, so when my wife is with me, I believe the suspension will be excellently set.
I've got 60k miles on it, without ever doing a single alignment.
My stock (from the factory) tires lasted me about 50k miles, and the next set of tires were second hand, are 50% worn after 12-13k miles. They're cheapies, and the road is pretty bad and hot out here (tires in South Florida wear much quicker than up north).

As far as spark plugs, at 60k miles, I'll be replacing them. They only cost me $20 for a set of 4. They're iridium.
I don't buy in the MPG gain hype of iridium, but they might last me more than regular spark plugs.
Anyway, regular spark plugs would have cost me $18, so I hope the $0.5 extra per spark plug, is well invested!


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## blackbird (Nov 6, 2017)

As long as you have adequate spark the old "copper core" conventional electrode plugs, platinum, and iridium should perform the same with respect to economy. One of the main reasons modern turbocharged engines use iridium plugs is for the service life. Platinum and double-platinum (has platinum part on both the center electrode and ground electrode/strap) normally have a very small amount of platinum material on the spark surfaces. It doesn't wear down like conventional plugs over time and they usually work great in naturally aspirated engines.

Most turbocharged engines run rich under boost to aid in cooling (the extra fuel absorbs heat from the combustion process and helps prevent detonation/knock). This can cause increased carbon build-up and deposits that can foul the spark plug. The very small platinum coated surface area can foul a lot easier and cause drivability problems and if you change them out at similar intervals to conventional plugs you'll pay a lot more.

The iridium plugs also have a very fine (thin) iridium center electrode but there's a lot more surface area so they're generally less prone to fouling problems than platinum plugs. The iridium material tends to retain heat that can also help burn off and keep carbon deposits from forming. That's one of the down sides in extreme engine builds with aftermarket big turbocharger builds running big power on a small displacement engine. If the combustion pressures get too high and the iridium plugs is too hot or even a normal heat range (capability for the plug to shed heat into the cylinder head) it's possible for the iridium to get superheated and cause engine destroying pre-ignition. That's one of the reasons why extreme engine builds and turbocharged racing cars often stick with conventional plugs swapped out more frequently.


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## ProDigit (Aug 31, 2015)

The Cruze 1.4l engine is more of a low-rev engine, and probably has a harder time getting rid of sooth.

Anyone knows how many miles you can get out of the stock spark plugs?
I'm at 63k now.


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## jblackburn (Apr 14, 2012)

ProDigit said:


> The Cruze 1.4l engine is more of a low-rev engine, and probably has a harder time getting rid of sooth.
> 
> Anyone knows how many miles you can get out of the stock spark plugs?
> I'm at 63k now.


That's why heat range is important.

60K. It was originally listed as 100K maintenance, then later changed to 60K in the owners manual. Most owners start having issues with them between 70-80.

Watch out for the coil pack boots breaking. Pull up GENTLY from both ends of the coil pack. Do not wiggle it - pull straight up.


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## dhpnet (Mar 2, 2014)

You will probably get more even wear, longer life, and better traction if you rotate the tires according to the manufacturer's specifications. They recommend rotating them for a reason. It's a good idea to start. America's Tire / Discount Tire will rotate them for free (and usually very quickly). 

My Owner's Manual recommends replacing the spark plugs at 97,500 miles. Replacing them at 60K won't hurt anything. I believe the engineers who designed this engine were competent. Unless you are noticing problems with your engine, you should be fine following the service interval in the Owner's Manual. 

NGK does not recommend using anti-seize on their spark plugs. They plate the threads with a material that should prevent corrosion between the head and the spark plug and help release the plug during removal. The NGK website also says that anti-seize acts like a lubricant and their tests show that using it can cause you to over-torque the spark plugs as much as 20%. This increases the risk of damaging the threads on the aluminum head and damaging the spark plug. I am pretty sure that the NGK engineers know what they are talking about, so I think it's fairly safe to trust them. Check their website for more info. 

Be sure to put dielectric grease on the rubber boots. This helps with a lot of problems including torn boots. 

If long life and low maintenance are important to you (which it sounds like they are), then go with the original equipment plugs. The original equipment plugs will last you the longest time. The copper plugs will perform slightly better, but you will need to check them regularly and replace them sooner.


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## dhpnet (Mar 2, 2014)

jblackburn said:


> That's why heat range is important.
> 
> 60K. It was originally listed as 100K maintenance, then later changed to 60K in the owners manual. Most owners start having issues with them between 70-80.
> 
> Watch out for the coil pack boots breaking. Pull up GENTLY from both ends of the coil pack. Do not wiggle it - pull straight up.


Mine is a '14 and it still says 97,500. When did they change this?


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## Merc6 (Jun 8, 2013)

dhpnet said:


> You will probably get more even wear, longer life, and better traction if you rotate the tires according to the manufacturer's specifications. They recommend rotating them for a reason. It's a good idea to start. America's Tire / Discount Tire will rotate them for free (and usually very quickly).
> 
> My Owner's Manual recommends replacing the spark plugs at 97,500 miles. Replacing them at 60K won't hurt anything. I believe the engineers who designed this engine were competent. Unless you are noticing problems with your engine, you should be fine following the service interval in the Owner's Manual.
> 
> ...





dhpnet said:


> Mine is a '14 and it still says 97,500. When did they change this?


As they kept discontinuing parts on the car. The car in 2011 started off with 100K 6 heat range plugs and then 2015 owners manual it was the 7 range and the shorter interval. The way my car was on coil packs I swapped plugs when the coil failed or the BKR7e's lost their V pattern. When I sold the car I had the BKR7EIX set that held gaps for almost a year and a half when I checked a month before trade. It also didn't help my stock plugs was gapped 0.016 and under and then the replacements at 0.017 on the 2nd coil pack.


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## ProDigit (Aug 31, 2015)

The spark plugs on my scooter used a stock 0.024 spacing, so 0.017 is not really a reason for concern (for swapping out), I believe.
0.01 is about the lowest that works. Any smaller, and the engine has trouble firing the mixture.

Talking of soot (or carbon buildup), 
What do you do, to clean the carburetors?
I hear water injection, or running a bottle of rubbing alcohol gets rid of carbon build up in minutes!


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## jblackburn (Apr 14, 2012)

ProDigit said:


> The spark plugs on my scooter used a stock 0.024 spacing, so 0.017 is not really a reason for concern (for swapping out), I believe.
> 0.01 is about the lowest that works. Any smaller, and the engine has trouble firing the mixture.


Runs like crap. They bog down like a pig.



> Talking of soot (or carbon buildup),
> What do you do, to clean the carburetors?
> I hear water injection, or running a bottle of rubbing alcohol gets rid of carbon build up in minutes!


Carbs? Huh?


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## snowwy66 (Nov 5, 2017)

ProDigit said:


> The spark plugs on my scooter used a stock 0.024 spacing, so 0.017 is not really a reason for concern (for swapping out), I believe.
> 0.01 is about the lowest that works. Any smaller, and the engine has trouble firing the mixture.
> 
> Talking of soot (or carbon buildup),
> ...


That was a common trick used in carbs when leaded gas was the thing. Today's gas don't have lead. Therefore, carbon buildup doesn't exist anymore. 

My very first motorcycle i bought brand new. Was an 82 yamaha bought in 84. I used leaded gas till i think about 25k miles. When it got sick. Dealer said carbon buildup. Start using unleaded gas. Around 1k miles the problem started getting better. Around 5k miles problem was gone.


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## ProDigit (Aug 31, 2015)

jblackburn said:


> Carbs? Huh?


Buh.. Typo, was probably distracted. I meant cylinders/valves.


And carbon buildup is definitely still a thing with unleaded....


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## dhpnet (Mar 2, 2014)

snowwy66 said:


> today's gas don't have lead. Therefore, carbon buildup doesn't exist anymore.


lol!!!


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## jblackburn (Apr 14, 2012)

ProDigit said:


> Buh.. Typo, was probably distracted. I meant cylinders/valves.
> 
> 
> And carbon buildup is definitely still a thing with unleaded....


Top tier fuel does a fine job on the intake valves of the port-injected (1st gen) engines.

Every...idk, 5 years or so, there's solvents like GM Top Engine cleaner and others on the market that will clean off the pistons.


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## Merc6 (Jun 8, 2013)

ProDigit said:


> The spark plugs on my scooter used a stock 0.024 spacing, so *0.017* is not really a reason for concern (for swapping out), I believe.
> 0.01 is about the lowest that works. Any smaller, and the engine has trouble firing the mixture.
> 
> Talking of soot (or carbon buildup),
> ...


If you get a chance, try 0.017 out on the Cruze. I promise you I didn't make it out of Yukon PA because I couldn't climb hills. I'm convinced it was intentionally set that low.


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## snowwy66 (Nov 5, 2017)

ProDigit said:


> Buh.. Typo, was probably distracted. I meant cylinders/valves.
> 
> 
> And carbon buildup is definitely still a thing with unleaded....


If we still had carbon build up. We'd still be suffering the same problems leaded gasoline caused.

How is it that running leaded gasonline caused build up. And switching to unleaded. Cleaned it out.

I"m willing to bet. That most of you weren't driving yet when carbon build up actually existed.


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## ProDigit (Aug 31, 2015)

snowwy66 said:


> ProDigit said:
> 
> 
> > Buh.. Typo, was probably distracted. I meant cylinders/valves.
> ...


Hmm...
I'm driving today.
It's not because fuel is much cleaner, that there's no more carbon build up,although it's rare to have it below 50k miles.


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## jblackburn (Apr 14, 2012)

snowwy66 said:


> If we still had carbon build up. We'd still be suffering the same problems leaded gasoline caused.
> 
> How is it that running leaded gasonline caused build up. And switching to unleaded. Cleaned it out.
> 
> I"m willing to bet. That most of you weren't driving yet when carbon build up actually existed.


2+2 =/= 6


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## snowwy66 (Nov 5, 2017)

jblackburn said:


> 2+2 =/= 6


and 8 + 8 = 1


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## snowwy66 (Nov 5, 2017)

ProDigit said:


> Hmm...
> I'm driving today.
> It's not because fuel is much cleaner, that there's no more carbon build up,although it's rare to have it below 50k miles.


Carbon was heavy from lead. Todays fuel boasts of techron to clean injectors and valves. There's that other company that boasts techrilene. 

Carbon buildup was a sympton of leaded gas. Today, people will drive their cars 250k miles and no one even cares or worries about carbon. Carbon buildup was a thing of the past. I don't know why it's of any concern today. It's not like any of us will ever have to worry about it. Unless you take your car to a country that might still sell leaded gasoline. If it still exists anymore. 

I had a motorcycle that suffered carbon build back when leaded gas was still around. Running unleaded cleaned it out. I was a mechanic for 12 years. Only had 2 cars that had carbon problems. Both were early cars that required lead. Not 1 unleaded car ever came in with a carbon problem. Unleaded gas has been out for 40 years. Lead went bye bye over 20 years ago. 

Sure we might get a little carbon in the engine. But this carbon buildup thing. That was a sympton long gone.


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## blackbird (Nov 6, 2017)

I'm kind of curious how the combustion process transforms a lead atom into carbon. Back in the days of leaded gasoline when most cars were carbureted, the primitive fuel management caused excessive fuel to be burned which could result in carbon build up. After all, gasoline is a _hydrocarbon_ and the combustion processes burns the hydrocarbons with oxygen and the byproduct can be excess carbon.

Leaded fuel could cause problems with spark plugs in that the very fine amounts of lead when burnt could eventually coat and foul the small electrodes of the spark plug, combined with lower quality plugs at the time, weaker ignition systems, and poor fuel management that did result in carbon deposits all added up to shorter plug life.

Lead Fouling | Shell Global


With modern direct injection engines and higher quality fuels (i.e. additive and detergent package) results in less carbon byproducts from the combustion process building up in the combustion chamber but there will still be some, especially in rich running, high compression, high boost small displacement turbocharged engines.

The other type of carbon buildup problems on modern direct injection (DI) engines isn't necessarily related to spark plugs is when carbon builds up on the surface of the intake valves because there isn't port fuel injection and the detergent in the gasoline constantly washing the valves down on the intake stroke. That carbon primarily results from heat and buildup of hydrocarbons from another source. Motor oil. Small traces of engine oil makes it past the valve seals over time, then with heat transferring through the valve stems from the combustion process causes it to "cook" and build up as the dried out carbon you see. That's one of the reasons why DI engines have very strict standards of motor oil that should be used.


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## dhpnet (Mar 2, 2014)

blackbird said:


> The iridium material tends to retain heat that can also help burn off and keep carbon deposits from forming. That's one of the down sides in extreme engine builds with aftermarket big turbocharger builds running big power on a small displacement engine. If the combustion pressures get too high and the iridium plugs is too hot or even a normal heat range (capability for the plug to shed heat into the cylinder head) it's possible for the iridium to get superheated and cause engine destroying pre-ignition. That's one of the reasons why extreme engine builds and turbocharged racing cars often stick with conventional plugs swapped out more frequently.


Interesting. But, a quick search shows that Iridium has better thermal conductivity than nickel (so called "copper plugs" actually use nickel for the ground and center electrode). I don't see how iridium could overheat like you say since it is better at transferring heat. Not arguing. I am genuinely interested in understanding. 

I work in the aviation industry. I have heard many times that double iridium plugs are by-far the best choice for the high performance turbo piston aircraft engines. 

Thermal Conductivity (lb/s Fahrenheit)
Cu = 48
Ir = 18.4
Ni = 7.58
Pt = 8.64

Iridium also has less electrical resistance than nickel (nOhm x m)
Cu = 16.78
Ir = 47.1
Ni = 69.3
Pt = 100

And, of course, iridium has a higher melting point, higher tensile strength and is harder than nickel.


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## ProDigit (Aug 31, 2015)

blackbird said:


> I'm kind of curious how the combustion process transforms a lead atom into carbon. Back in the days of leaded gasoline when most cars were carbureted, the primitive fuel management caused excessive fuel to be burned which could result in carbon build up. After all, gasoline is a _hydrocarbon_ and the combustion processes burns the hydrocarbons with oxygen and the byproduct can be excess carbon.
> 
> Leaded fuel could cause problems with spark plugs in that the very fine amounts of lead when burnt could eventually coat and foul the small electrodes of the spark plug, combined with lower quality plugs at the time, weaker ignition systems, and poor fuel management that did result in carbon deposits all added up to shorter plug life.
> 
> ...


So with all the technical background of carbon buildup,
What would you say to those who have the older port injection, and those with the newer direct injection 1.4l turbo engines?
Low rev, turbo, all add to deposit buildup.
So far, I haven't heard too much about engines dieseling, but there is a possibility to remove the carbon deposits if it does..

Or would you say to not care about carbon deposit (as it causes a minimal increase in compression ratio, and thus, higher efficiency)?


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## susan james (Jun 22, 2016)

People on this post trail seem to like the NGK plugs. What do these plugs do to improve performance?


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## booyakashao (Dec 7, 2018)

NGK is a manufacturer of spark plugs that is well known. Honestly you could go with ACDelco as well. The plugs recommended for a cruze does not "improve performance" and I've heard copper plugs perform better, but for the average driver that's not necessary. Iridium plugs from NGK, ACDelco, or others will last longer and that's why those are recommended for use on cruze.


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## jblackburn (Apr 14, 2012)

susan james said:


> People on this post trail seem to like the NGK plugs. What do these plugs do to improve performance?


Improved heat scavenging helps increase timing and power at the low end of the rev range on the 1.4 on plugs that do not use a platinum ground strap. We've found the Bkr series plugs work well in these motors BUT the need for maintenance is stepped up because of gap erosion.


booyakashao said:


> NGK is a manufacturer of spark plugs that is well known. Honestly you could go with ACDelco as well. The plugs recommended for a cruze does not "improve performance" and I've heard copper plugs perform better, but for the average driver that's not necessary. Iridium plugs from NGK, ACDelco, or others will last longer and that's why those are recommended for use on cruze.


NGK is the OEM supplier of the AC Delco 41-12x plugs the Cruze uses (and most of GMs other plugs as well). They are a rebranded IFR6/7 series plug.

Sent from my SM-G950U using Tapatalk


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## snowwy66 (Nov 5, 2017)

I remember when autolite and motorcraft were the plugs. Now it's ND & NGK.


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