So I replaced my spark plugs today.....

[ScottyBoy]

I finally got around to changing out my spark plugs on my Suburban today. I ended up getting a set of plug wires from NAPA. So I get the old plugs out and see that they arent AC Delcos, but they are Denso plugs. Did GM install Denso plugs in the factory? Also, I noticed some deposits on my plugs and I'm not sure if this would be normal for a truck with 90,000 miles, or if there is something I should be concerned about. Also, the plug closest to the firewall on the driver's side had oil on it, the others either didn't or had just a trace of oil on them.

Here are 3 plugs compared to a new plug.

Here is a close up of the electrodes

And here is the one that had the oil on it.

I also would like to add that the plug closest to the firewall was a SEVERE pain! I was cussing and getting upset about it. First the wire ripped, then I had to spend like 15-20 minutes getting the the end of the plug boot off. Then I was finally able to get to the plug, but then the socket wouldnt go on because the metal tip from the spark plug wire was still on the plug. Needless to say, I have cuts all on my hands and busted knuckles, but I finally got it swapped out.

 

[La Bestia]

Did GM install Denso plugs in the factory?

Nope, unless they pulled some sneaky shit when I wasn't paying attention. Busted knuckles are what GM sparkplugs are known for . I will wait for someone smarter and more sober to comment on the look of the old plugs but hope I helped ya a little.

 

[ScottyBoy]

Yeah, they were Denso's alright. Here is a pic of the Delco next to the Denso.

 

[La Bestia]

That definitely looks like 2 spark plugs

I really hope someone sober gets here soon to rescue me.

 

[Wyley87]

any chance your truck was made for export?

 

[Sunset_Z28]

Sounds like you had the kind of luck I had when doing mine. I wasn't planning on replacing my wires but I got to the last one on the passenger side facing the firewall and pulled the wire in two. Needless to say I had to make a run to Napa as well.

 

[Texas Jim]

Scotty,
Actually it looks like most of the oil was on the OUTSIDE of the plug...not in the cylinder and on the electrode...

 

[Bigredmariner]

I would say they don't look unusual to me. I wouldn't worry too much about the oil on the threads either. There isn't a bunch of build up on the plugs, the insulators still look white-ish and you have some burn away of the electrode. Nothing too out of the ordinary for a street truck.

 

[Wyley87]

i was actually thinking a seeping valve cover gasket. but the whole outside plug that wasn't in the boot should have oil on it.

 

[ScottyBoy]

any chance your truck was made for export?

AHA! That may be why, because according to my VIN my truck was built in Mexico.