just bought a 11 Jeep Liberty with the 3.7L motor....and the owner's manual is saying to swap plugs every 2yrs/32K miles....question is...why??

I just ordered Autolite iridium plugs for it, OEM are NGK...so are they REALLY going to foul or something at 2yrs/32k??? never heard of changing them so often...

thanks for any help!

Mike

Do they use regular copper plugs? Back in the day copper plugs used to be changed every 30K miles. Not everyone uses platinum plugs.

looks like it....from the NGK site...

V-Power Plug, 14mm Thread Size, 19mm (3/4") Reach, 5/8" (16mm) Hex Size, Gasket Seat, Resistor, Extended Projected Tip, Solid Terminal Nut, ISO Length, V-Power (V-Grooved Centere Electrode), .043" (1.1mm) Gap, Heat Range 6

NGK's unique V-Power design directs the spark to the edge of the electrode where it develops more rapidly, this increases ignitability even in lean burn conditions. In addition the NGK V-Power plug has all the features of their traditional plugs including corrugated ribs, pure alumina silicate ceramic insulator for greater strength and better heat transfer, copper core and triple interior seal.

Hmm, I thought all modern cars were now good for 100+K mile intervals for plugs. My plugs are original on my Toyota at 117,000. I'm in no hurry to change them. I wouldn't want to pay for a tune up every 30K. Just make sure to get proper plugs to eliminate this issue.

yep, I'm used to japanese maintenance....never ever heard of changing plugs so often....

assuming a good set of iridium will go at least 100K.

Does the Jeep have a cylinder deactivation system, my brothers 08 300, 5.7 has regular 30k plugs but it has the MDS, were at certain speeds 2-4 cylinders shut down, we put platinum plugs in and within a short time the engine went into limp mode, switched back to regular copper 30k plugs and problem went away.

Have no idea why it needs specifically copper plugs but it does, the V6 300 and SRT8 models have 100k platinum plugs

My Ram has 16 plugs on it, 8 Copper Core and 8 Iriduim. I have NO idea why, or what it does for the engine to have 2 plugs per cylinder, but they are likely being conservative with the interval. I am at roughly 60k miles and have never changed them. I check them periodically, and the truck runs fine, so I will change them when I get home from my deployment.

And yes on the cylinder deactivation, iridiums are not good for those motors. However, I dont believe the 3.7L in your liberty has them bagwell.

Copper core plugs are cheap at least.

They still use copper spark plugs? Dang. I thought for sure OEM plugs would be iridium or similar by now.

I'm sure you can just switch to iridium and be good for a longer interval?

No, you cant, well you could, but they would be fouled out in the same amount of time due to engine design. This has been covered over and over again on the Mopar forums I belong to. Just change them yourself to save some cash, the dealers want upwards of $400 to do it, the plugs can be had for about $30 total, and it only takes an hr or 2 for the most inexperienced person. So I would save the hassle of waiting at the dealership, by the plugs, anti sieze, any tools you might not already have and pay yourself the $250+ for the job.

Wow that sucks. I'm guessing most owners will just fork over the money for new plugs to the dealer every 2 yrs/32k miles?! Sucks

No, most people assume that they are like every other car, and have a 100k mile interval. Then when they start having problems at 60k, they whine and cry saying "my chrysler/dodge/jeep/ram/whatever is a piece of crap!" Well, no, it isnt, you just did not maintain it. And unfortunately no law exists stating dealerships are required to disclose such information at point of sale. It is entirely the customer's responsibility to do their research and ask the important questions on their own. Perfect example is the Timing Belt replacement cost on most Lexus vehicles. If many people knew before they drop $35,000-$80,000, that between 60-90k miles they would have to fork over upwards of $1,000 for a BELT change, I'm sure it would turn off a lot of buyers. Not hating on Lexus, but using them as a non-biased example. Thats why they dont advertise it. However, if you ask at the point of sale, and they are a good salesperson, they will gladly tell you. Its one of those "Better to ask forgiveness than permission" kinds of things.


All vehicles come with an owners manual in one form or another, and all manual's have service intervals listed, and the dealer can tell you as well, without obligating you to let them do the work. You will void no warranty as long as you are using OEM type parts and keep your reciepts with dates, and fill out your maintenance log in the back of your owners manual.


Just a damn shame that so many people discount great vehicles because they have problems with them when they did not follow the proper maintenance schedule. I see it all the time and ALOT of great cars get a bad rap because of it. (Not saying this applies to anyone here, just in general.)

just wanna point out that copper plugs do produce a better spark than precious metal plugs.

the only reason that platinum/iridium plugs are in widespread use is because back when FWD cars took over the manufacturers found that doing spark plugs every 30-40k miles on a FWD V6/V8 was a real pain, so they started using long life precious metal plugs to lessen the workload for the mechanics and appease consumers.

On most RWD modern cars (short of luxury cars which can afford the extra price and arent focused on performance gains) with easily accessible spark plugs manufacturers will still stick to copper plugs for better performance and emissions.

I run copper plugs (NGK V-Power in fact) on my LS and my MA70. All the FWD cars i've owned (camrys mostly) got platinum plugs unless they were 4cyl.

They have dual plugs because the computers monitor the plug temperatures, especially when the MDS kicks in. Copper provides a hotter spark, and iridium can overheat, especially at highway speeds where they are firing much more often. The dishing of the hemispherical chambers also affects the plugs, since any fuel not burned naturally sits at the bottom of said sphere. With the hotter plugs, this problem is mostly alleviated.

Agreed. For about $ 2 a pop, tough to argue. When you buy iridiums for $ 7 each, you are really spending the same amount, though, since you get 90K for $ 6 with copper (3 changes) and 100K with iridiums for $ 7. The real kicker is if you pay someone to change them for you.

Agreed.

Agreed, as I said above. As more manufacturers try to lessen the maintenance costs as a differentiator between them and a competitor, this will become more common. I mean, when almost every car in a segment is similarly priced, the true TCO is what comes into play. And since more manufacturers are starting to include maintenance, they try to keep those costs to the dealerships at a minimum so as not to affect their bottom line, too.

Big Mack

I havent heard of a car need new plugs like that for a looooong time now. Seems antiquated and old school

Yes, the 100,000-mile platinum plugs do lessen the number of times they have to be changed, but a major problem can arise with leaving them in that long, even if anti-seize-compound is used on the plug's threads at the factory when they are first screwed in. Over a number of years and 100,000 miles, the accumulated engine-heat (sometimes from nearby exhaust parts at up to 800-900 degrees) can burn the plugs into the cylinder-head threads so tightly that it is very difficult or impossible to unscrew them and get them out. I've heard of cases where technicians have either had to drill them out and re-thread the head, or simply replace the head altogether.

Similiar problems, of course, can sometimes happen on the exhaust-mainfold/shield where the spark-plug-like oxygen-sensors screw in.