2004 Saab 9-3 Platinum NGK Plugs 55k

[JHZR2]

My car has been telling me that a Main service is necessary, and so I decided to do the belt and plugs, which are 60k items at 55k.

Belt didnt go so well due to minimal space on a FWD car to access. Plugs were easy as one would expect from a 4cyl car.

Car runs great. Averaged nearly 38 MPG on my last trip, which was about 180 miles each way.

First pulled the plastic front cover and the metal cover over the coils:

Easy to remove the coils with a 10mm socket. Went after each plug.

The passenger side end plug:

Next one in:

Next one:

Driver's end

The spec for gap is 0.9-1.0mm for the gap. I have a wire gauge set and the two closest were 0.882mm and 1.02mm as I recall. The new replacement plugs (same NGK plugs that came out of the car) could fit the smaller feeler with just the tiniest bit of slop, and the bigger one would not fit.

The replacements had a tiny bit more slop with the smaller feeler, and would not accept the 1.02mm feeler, but would allow it a bit further in than the new plugs.

So only the slightest errosion after 55k. Not really sure why they even recommend doing them at 60k service. Access is super easy and the car seems easy on plugs, even if it is a turbo.

 

[dparm]

Platinum can easily go 100k. I bet those could've stayed in for another 20k+. Yours wore well. Consistent and correct wear pattern.

I laugh when I hear people changing platinum plugs yearly. Money and time down the drain. I changed mine at 50k and upon seeing them my dad joked, "those things are barely half-used". (he worked for Bosch for 25+ years)

The iridiums coming in Toyotas are rated as 200k+. They truly are "lifetime". I read a good SAE paper written by Denso that literally showed how the iridiums pretty much never wear out under normal use.

 

[JHZR2]

Yeah, it suprised me that saab recommended 60k. But Im planning to put a lot of miles on the car in the next little while so I wanted to get the main and 60k service past me... so I did them.

I was thinking that maybe because it is a turbo there would be a difference, no dice.

I think my car was a 7/03 build, though an MY04. I that is true, then the plugs have been in 8 years. They were a bit stiff to come out. I have to go back and forth a few times... That's what would scare me with 100k or 200k plugs. If/when the time comes to get them out, it might be really tough...

Not a huge deal given the access on a 4 cyl. But Id hate to have a bum plug in the rear bank of a FWD v6 car. Just think of the hassle!

 

[Garak]

Originally Posted By: JHZR2
My car has been telling me that a Main service is necessary, and so I decided to do the belt and plugs, which are 60k items at 55k.


Plugs definitely look nice. My old 1991 Audi has a similar service interval for plugs, but Bosch specs copper for it, and they're easy to change, too.

Timing belts - don't get me started on those. The Audi is still sitting and waiting for the water pump (and the incidental timing belt to go with it). The Ford 300 has it right - no timing belt or chain, for that matter. Just a gear.

 

[mormit]

NGK makes a good spark plug. In my experience, Denso does not.

I made the mistake of running a set of Denso iridiums on my Volvo S40. They went 20,000 miles before they started missing. Pulled them and they were very badly worn. I should have thrown a cheap seat of $1.50ea Bosch coppers every 12 months instead.

I put a set of OEM Volvo plugs made my who I don't know, Bosch platinum probably. They are fine after over 50,000mi. Here forward I'll stick with Bosch or NGK. Denso? Not so.

 

[friendly_jacek]

Originally Posted By: dparm


The iridiums coming in Toyotas are rated as 200k+. They truly are "lifetime". I read a good SAE paper written by Denso that literally showed how the iridiums pretty much never wear out under normal use.


Actually, 120,000 miles. Close if you meant km. But 200,000 miles is doable with good plugs. People changed Denso long life plugs on RAV4 and documented like new condittion. I'm only at 40,000 miles and mine also look like new. This is from a RAV4 with 115,000 miles:

On the other hand, I just changed NGK long life iridiums in Corolla at 75,000 and they don't look as good with ground strap wear outside the iridium part:

BTW, Denso are made in Japan and NGK were made in USA, not sure if it matters.

 

[dparm]

Yes, I meant KM. My mistake.

As for the person whose Densos wore out in 20k -- if you are running the 0.4mm-tip "high-performance" variant, they flat-out tell you to change them more often:


Power plugs, with their .4mm center electrode, have been developed for performance applications. Because gradual wear will “round-off” firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. For this reason, DENSO advises replacement after 30,000 miles.



FYI, NGK used to be built under license from Bosch...

 

[friendly_jacek]

Originally Posted By: dparm

FYI, NGK used to be built under license from Bosch...


Didn't know that. That would explain a lot. I just used Autolite iridium in Corolla as I could get them very cheaply after rebates. However, poor machining quality and made in mexico. We will see.

 

[dparm]

It's not widely known. My dad used to work for Bosch and told me this.

 

[ltslimjim]

I'd be willing to try a Denso or NGK Iridium, if only my car would like them.

Since I'm not sure, I don't want to invest and then pull them prematurely, since this engine burns hotter in the combustion chamber(lean burn), and most swear by using the stock NGK V-Grooved in this particular app.

 

[Patman]

Originally Posted By: dparm


The iridiums coming in Toyotas are rated as 200k+. They truly are "lifetime". I read a good SAE paper written by Denso that literally showed how the iridiums pretty much never wear out under normal use.


There is a guy on the 8th gen Honda Civic forum who has over 600,000 miles on his Civic and is still running the original NGK Laser Iridium plugs! He even changed his engine around the 300k mark and reused the plugs! He takes them out every once in a while and cleans them, and they've been working fine so he just keeps using them! Makes me feel foolish for taking mine out at 80k! I've got Champion iridiums in there now and I'll definitely leave them in for at least 100k or more.

 

[ltslimjim]

^WOAH?! How did he rack up that many miles on an 8th gen so quickly? Crazy.

 

[FZ1]

Plugs are a time OR miles replacement item. 7 years is about the max time to leave them in. Personally,6 years max,for me. It's just as much about "Seize Life" as it is about "Plug Life."

 

[friendly_jacek]

Another thing to consider is engine hours. The pristine Densos in the the pictures I posted in my previous post had under 2000 hrs in mostly hwy driving at 115,000 miles. The worn NGK had over 3000 hrs in mostly city driving at 75,000 miles.

 

[tom slick]

JHZR2, Thank you, Thank you, Thank you for well lit, in focus, pictures. That's a rarity around here!

 

[JHZR2]

Originally Posted By: ltslimjim
^WOAH?! How did he rack up that many miles on an 8th gen so quickly? Crazy.


Why would anyone waste the money putting a new engine in a 300k car? Id think that lots of other stuff would be worn, even with all highway use.

Not sure why iridium plugs would be used there anyway. Changing on an I4 engine is a no brainer. Here's why:

Originally Posted By: FZ1
Plugs are a time OR miles replacement item. 7 years is about the max time to leave them in. Personally,6 years max,for me. It's just as much about "Seize Life" as it is about "Plug Life."

 

[ddean]

The NGK Laser series plugs are very long lasting, even the lesser platinums. I saw a picture of 137K factory plugs from an Ecotec and they were worn out (OEM AC Delco Pro which are NGK Laser Platinum. But this Saab's engine is COP ignition unlike the NA Ecotecs so the plugs will wear much more evenly. GM has actually gone over to NGK Laser Iridium plugs for replacement parts and was OEM on many of the final DIS ignition engines.

 

[Patman]

Originally Posted By: ltslimjim
^WOAH?! How did he rack up that many miles on an 8th gen so quickly? Crazy.


He is some sort of courier (delivering meds) so he's on the road for 8 hours every night.

 

[Patman]

Originally Posted By: JHZR2


Why would anyone waste the money putting a new engine in a 300k car? Id think that lots of other stuff would be worn, even with all highway use.



His original engine actually was fine, he thought it had seized up, and he had a used shortblock that he bought on E-bay for $150 a while before that, so he put it in (himself, so there was no labor cost) But then it turned out to just be a seized starter motor, so it's unfortunate that he went to all that trouble and replaced a perfectly good engine. But he now has that original engine as a spare, and he can throw it back in when this one lets go.

 

[dparm]

Denso's Iridium plugs are unique versus Bosch & NGK because they use a finer electrode. That's why I use them (0.4mm!).