Replacing spark plugs

My 4.0 6cyl, albeit in a TJ, uses NGK ZFR5N plugs with a 35 thousandths
gap. That's what my owners manual says. I can't imagine platinum plugs
being "required".

tinman wrote:
> Hi,
>
> I have my '99GC 4.0L 6cyl in the shop for a 90K maintenance. The
> mechanic
> just called me and says that he found platinum plugs in there and so
> he must
> replace them with platinum plugs. He insists that he cannot replace
> platinum
> plugs with regular plugs (which are included in the maintenace charge)
> and
> wants to charge me $12 extra per plug. Is this true? I do not intend
> to keep
> the car long enough to justify the benefit of platinum plugs, so I'm
> inclined
> to go with regular plugs. Is there any downside to this or am I just
> getting
> scammed?
>
> thanks.
>
> -Tin
>

--
FRH

"DougW" > wrote in message
news
> Jeff Strickland wrote:
>
>> I once owned a GM car that needed something special in the plug. The
>> catalog at the parts house gave a listing for a plug that was missing
>> a letter or number somewhere in the middle, and this missing digit
>> denoted that the plugs were "high output".
>
> That missing letter probably indicated no internal resistor.
>


Agreed. Whatever it indicated, it was important.

"Jeff Strickland" > wrote in message
news:%rORh.5187$Cl.3582@trndny08...
>
> "Mike" > wrote in message
> ...
>>
>> "Jeff Strickland" > wrote in message
>> news:2RCRh.265$eC.105@trndny03...
>>>
>>> "Mike" > wrote in message
>>> ...
>>>>
>>>> "Jeff Strickland" > wrote in message
>>>> news:qWgRh.5945$bM1.1484@trnddc03...
>>>>>
>>>>> "tinman" > wrote in message
>>>>> oups.com...
>>>>>>
>>>>>> Thanks, Doug. I'm just going to insist he replace them with regular
>>>>>> plugs and I'll take the *chance* of the engine blowing up
>>>>>>
>>>>>> thx.
>>>>>>
>>>>>> -Tin
>>>>>
>>>>>
>>>>> There's no danger of the motor blowing up. It just won't run well.
>>>>>
>>>>
>>>> The platinum plugs will last longer but there will be no difference
>>>> in the way the engine runs no matter which plug is used.
>>>>
>>>
>>> Not true IF high power plugs are required.
>>
>>
>> Never heard of "high power plugs", care to explain what they are and
>> when the are required ?
>>
>>
>
>
> Poor choice of words. There are different varities of plugs, some of them
> are designed to provide high output. If high output plugs are called for,
> they must be used. I agree with you, if high output plugs are not called
> for, they probably are not worth the added cost.
>

There is no such thing as " high output plugs".



> I once owned a GM car that needed something special in the plug. The
> catalog at the parts house gave a listing for a plug that was missing a
> letter or number somewhere in the middle, and this missing digit denoted
> that the plugs were "high output". I attempted to use the plugs, and the
> car would not run for crap. Since I was not able to understand all of the
> digits of the part number, I missed the significance of a digit that was
> not on the new plugs that I had in my hand.


I'll say it again, there's no such thing as "high output plugs". My bet
is that the parts guy gave you a shorter reach spark plug instead of a long
reach plug. I have run across that before on the older GM's and they will
run like crap with the shorter plugs installed. If the missing digit had
been at the end it would have been an "R" designating a reistor plug. That
wouln'd make the car run poorly. A missing digit in the middle would either
be plug reach or heat range.

I'll bet what the parts guy was trying to tell you is that the sprk plugs
were listed for the "high output" engine option, not that it was a "high
output" spark plug

>
> I am not saying that the OP needs platinum plugs, I'm saying that there is
> benefit in some motors for them.


Platinum plugs will last longer, that's all. They will not make the
engine run an different.



>
>
>
>
>
>
>>>
>>> I agree that platinum plugs won't hurt, and they could help. But if they
>>> are REQUIRED then they have to be used.
>>
>> I have never seen an engine that REQUIRED plantinum plugs. Platinum
>> plugs are usually used in applications where the plugs are a bitch to
>> replace. The are generally good for 60,000 - 100,000 miles. I have seen
>> regular plugs used in place of platinums quite often and they perform no
>> differently except they don't last as long.
>>
>>
>>>
>>> Having said that, I do not believe they are required.
>>>
>>>
>>>
>>>
>>>
>>
>>
>

"Mike" > wrote in message
...
>
> "Jeff Strickland" > wrote in message
> news:%rORh.5187$Cl.3582@trndny08...
>>
>> "Mike" > wrote in message
>> ...
>>>
>>> "Jeff Strickland" > wrote in message
>>> news:2RCRh.265$eC.105@trndny03...
>>>>
>>>> "Mike" > wrote in message
>>>> ...
>>>>>
>>>>> "Jeff Strickland" > wrote in message
>>>>> news:qWgRh.5945$bM1.1484@trnddc03...
>>>>>>
>>>>>> "tinman" > wrote in message
>>>>>> oups.com...
>>>>>>>
>>>>>>> Thanks, Doug. I'm just going to insist he replace them with regular
>>>>>>> plugs and I'll take the *chance* of the engine blowing up
>>>>>>>
>>>>>>> thx.
>>>>>>>
>>>>>>> -Tin
>>>>>>
>>>>>>
>>>>>> There's no danger of the motor blowing up. It just won't run well.
>>>>>>
>>>>>
>>>>> The platinum plugs will last longer but there will be no difference
>>>>> in the way the engine runs no matter which plug is used.
>>>>>
>>>>
>>>> Not true IF high power plugs are required.
>>>
>>>
>>> Never heard of "high power plugs", care to explain what they are and
>>> when the are required ?
>>>
>>>
>>
>>
>> Poor choice of words. There are different varities of plugs, some of them
>> are designed to provide high output. If high output plugs are called for,
>> they must be used. I agree with you, if high output plugs are not called
>> for, they probably are not worth the added cost.
>>
>
> There is no such thing as " high output plugs".
>
>
>
>> I once owned a GM car that needed something special in the plug. The
>> catalog at the parts house gave a listing for a plug that was missing a
>> letter or number somewhere in the middle, and this missing digit denoted
>> that the plugs were "high output". I attempted to use the plugs, and the
>> car would not run for crap. Since I was not able to understand all of the
>> digits of the part number, I missed the significance of a digit that was
>> not on the new plugs that I had in my hand.
>
>
> I'll say it again, there's no such thing as "high output plugs". My bet
> is that the parts guy gave you a shorter reach spark plug instead of a
> long reach plug.


Your bet would cost you money. The two plugs I had were physically identical
in size, the difference was internal and was denoted by a missing digit in
the part number on the new plugs. The digit was a C if my memory is correct.

It doesn't really matter what my particular experience was. My point is, if
there is a requirement for the digit, then one must be sure the digit is
there. In my case, a digit was missing and the plugs did not work. Does that
digit denote Platinum? Can Platinum plugs be made both with and without the
digit my plugs were missing? My guess is that the missing digit had nothing
at all to do with the platinum content, and I'm certain that neither plug I
had was platinum.

The following excerpt is from the 2003 Mopar Spark Plug Catalogue (page 9)

"The spark plugs below are specifically designed by Bosch for the optimum
performance of your Mopar engine. Each package contains four spark plugs."
and then lists the engines are recommended sparks.

I'll forward a copy to Bill for his records.


"Mike" > wrote in message
...
>
> "Jeff Strickland" > wrote in message
> news:%rORh.5187$Cl.3582@trndny08...
>>
>> "Mike" > wrote in message
>> ...
>>>
>>> "Jeff Strickland" > wrote in message
>>> news:2RCRh.265$eC.105@trndny03...
>>>>
>>>> "Mike" > wrote in message
>>>> ...
>>>>>
>>>>> "Jeff Strickland" > wrote in message
>>>>> news:qWgRh.5945$bM1.1484@trnddc03...
>>>>>>
>>>>>> "tinman" > wrote in message
>>>>>> oups.com...
>>>>>>>
>>>>>>> Thanks, Doug. I'm just going to insist he replace them with regular
>>>>>>> plugs and I'll take the *chance* of the engine blowing up
>>>>>>>
>>>>>>> thx.
>>>>>>>
>>>>>>> -Tin
>>>>>>
>>>>>>
>>>>>> There's no danger of the motor blowing up. It just won't run well.
>>>>>>
>>>>>
>>>>> The platinum plugs will last longer but there will be no difference
>>>>> in the way the engine runs no matter which plug is used.
>>>>>
>>>>
>>>> Not true IF high power plugs are required.
>>>
>>>
>>> Never heard of "high power plugs", care to explain what they are and
>>> when the are required ?
>>>
>>>
>>
>>
>> Poor choice of words. There are different varities of plugs, some of them
>> are designed to provide high output. If high output plugs are called for,
>> they must be used. I agree with you, if high output plugs are not called
>> for, they probably are not worth the added cost.
>>
>
> There is no such thing as " high output plugs".
>
>
>
>> I once owned a GM car that needed something special in the plug. The
>> catalog at the parts house gave a listing for a plug that was missing a
>> letter or number somewhere in the middle, and this missing digit denoted
>> that the plugs were "high output". I attempted to use the plugs, and the
>> car would not run for crap. Since I was not able to understand all of the
>> digits of the part number, I missed the significance of a digit that was
>> not on the new plugs that I had in my hand.
>
>
> I'll say it again, there's no such thing as "high output plugs". My bet
> is that the parts guy gave you a shorter reach spark plug instead of a
> long reach plug. I have run across that before on the older GM's and they
> will run like crap with the shorter plugs installed. If the missing digit
> had been at the end it would have been an "R" designating a reistor plug.
> That wouln'd make the car run poorly. A missing digit in the middle would
> either be plug reach or heat range.
>
> I'll bet what the parts guy was trying to tell you is that the sprk plugs
> were listed for the "high output" engine option, not that it was a "high
> output" spark plug
>
>>
>> I am not saying that the OP needs platinum plugs, I'm saying that there
>> is benefit in some motors for them.
>
>
> Platinum plugs will last longer, that's all. They will not make the
> engine run an different.
>
>
>
>>
>>
>>
>>
>>
>>
>>>>
>>>> I agree that platinum plugs won't hurt, and they could help. But if
>>>> they are REQUIRED then they have to be used.
>>>
>>> I have never seen an engine that REQUIRED plantinum plugs. Platinum
>>> plugs are usually used in applications where the plugs are a bitch to
>>> replace. The are generally good for 60,000 - 100,000 miles. I have seen
>>> regular plugs used in place of platinums quite often and they perform no
>>> differently except they don't last as long.
>>>
>>>
>>>>
>>>> Having said that, I do not believe they are required.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>
>

Depends on where you live. If your engine is spec'd with platinum plugs
for emissions [should be in your owners manual] then a mechanic might
get in trouble replacing them with anything else, depending on the local
smog laws.

You could always call a dealer parts place and ask them if that engine
spec's platinum plugs as oem. Apparently some of the 99 engines do.
A dealer parts department would also be able to tell you if you must
replace them with platinum for smog reasons or not.


tinman proclaimed:

> Thanks, Doug. I'm just going to insist he replace them with regular
> plugs and I'll take the *chance* of the engine blowing up
>
> thx.
>
> -Tin
>
>
>>That's a load of bull.
>>
>>For that much you may as well go buy six plat plugs like the ones
>>that are in there and take them to the mechanic to install. Just remind
>>them to take off the cost of OEM regular plugs from your ticket or give
>>you the plugs since you paid for them.
>>
>>--
>>DougW
>
>
>

Looks like it, the Mopar part number is
Mopar SP000ZFR5N Resistor Copper Plug

The only mention I can find of platinums is for the HO 4.7

Ask your mechanic if he has a smog license and wants to keep it.
Some states are more hostile than others regarding smog scams.


billy ray proclaimed:

> That engine came from the factory with copper Champions as your 'mechanic'
> well knows.
>
> If you have had no drivability problems with the Platinums (I haven't in 3
> Jeeps) you can continue with them but be advised Bosch Platinums RETAIL for
> less than $2.50 each.
>
>
>
> "tinman" > wrote in message
> oups.com...
>
>>Hi,
>>
>>I have my '99GC 4.0L 6cyl in the shop for a 90K maintenance. The
>>mechanic
>>just called me and says that he found platinum plugs in there and so
>>he must
>>replace them with platinum plugs. He insists that he cannot replace
>>platinum
>>plugs with regular plugs (which are included in the maintenace charge)
>>and
>>wants to charge me $12 extra per plug. Is this true? I do not intend
>>to keep
>>the car long enough to justify the benefit of platinum plugs, so I'm
>>inclined
>>to go with regular plugs. Is there any downside to this or am I just
>>getting
>>scammed?
>>
>>thanks.
>>
>>-Tin
>>
>
>
>

I would wonder if your GAP was off.
Someone can correct me...but when your GAP is too big, if you draw the
curve of how much current is at the plug when it sparks, you'll see
that this takes longer to achieve then when it's GAP'd properly.
So, you lose some power.
Putting in different "types" of plugs with different metal contacts
probably means your timing will change too (this is on the matter of
milliseconds though!
The different materials are to reduce oxidation from the sparking and
to allow for hotter applications (more current).

If you go with hotter plugs, you might want to upgrade your plug wires
too (drawing more current, wires heat up some).

Anyhow, just replaced mine with OEM plugs and runs great! If you
change plugs and things run better...odds are the gap was off or the
plugs were dirty!
I hadn't changed plugs until 100,000km and the GAP was HUGE (twice the
suggest gap of 35thou).

Plugs cost me $20canadian.

cheers

On Apr 5, 8:50 pm, "Jeff Strickland" > wrote:
> "tinman" > wrote in message
>
> oups.com...
> > I have my '99GC 4.0L 6cyl in the shop for a 90K maintenance. The
> > mechanic
> > just called me and says that he found platinum plugs in there and so
> > he must
> > replace them with platinum plugs. He insists that he cannot replace
> > platinum
> > plugs with regular plugs (which are included in the maintenace charge)
> > and
> > wants to charge me $12 extra per plug. Is this true? I do not intend
> > to keep
> > the car long enough to justify the benefit of platinum plugs, so I'm
> > inclined
> > to go with regular plugs. Is there any downside to this or am I just
> > getting
> > scammed?
>
> > thanks.
>
> > -Tin
>
> It may or may not be a load of crap. It doesn't matter what he found, it
> only matters what the design calls for. I don't know what they designed for
> that motor, but my 258 (4.2L, sotrta) just takes standard plugs. I can't
> imagine your 4.0L requires platinum plugs, I suspect a previous owner put
> them in, or if you are the previous onwer then a shop installed them for you
> for any number of reasons.
>
> What I can say with certainty is that if you need high performance plugs,
> and you get standard plugs, the motor won't run worth a ****.
>
> I once owned a brand spanking new GM car with a High Output (quotes needed
> there) 2.8L V6 that -- I swear to God -- could not get out of its own way.
> Well, by and by I decided to replace the spark plugs because it was time. I
> went to the corner store and they looked up in the catalog, and came back
> with the "right" plugs. I installed them, and went for a test drive on the
> main drag in my town. Not only couldn't I get out of my own way, I became
> serious problem to the general population also using the main drag. I got
> back to my driveway, and checked EVERYTHING. Yes, everything. I had to take
> the car to the local tune up shop, and the guy pulled a plug and reported,
> "here's your trouble." It turns out the plug requirement was for some
> Hot-Snot Copper Core something or other, but all I had was regular snot. I
> took the regular snot and the mechanic's bill to the auto parts store, but
> all I got back was the cost for the crappy plugs.
>
> The moral of the story is, you might need hot-snot spark plugs, in which
> case you should get them. I think you can use the regular snot plugs though,
> and save several dollars.