Best Spark Plug?

[akauth]

Originally posted by KLS
The Denso IK series of plugs are high performance and normal life span. The electrode is .4 mm diameter.

Denso's other iridium plugs have a .7 mm diameter electrode and are high mileage, normal performance. These have the 100,000 mile replacement recommendation. How do you unscrew spark plugs with 100,000 miles of baked-on carbon in the threads?

Ken

Kens, right. Unless you go to the .7mm iridium, I don't think you're really going to see enough of a performance gain to justify the cost because you're still going to have to change the plugs whether you spent $3 or $15. But the "old" perfomance or the engine at that at that time change should definitely be better.

But if you could get 50,000 or 60,000 out of the iridiums (even if they were rated for 100,000) I'd probably go for them. But the way they are now, unless they really stayed that much cleaner at 29,000 miles nad you're getting better gas mileage than you would have otherwise, you'd be better off with the cheaper Bosch plat +4 plugs. Or changing plugs every 12,000 and putting in $2 to $3 NGK plugs (if you want to keep squeaky clean plugs).

Never really thought about it, but Ken does bring up a good point about pulling that carbon on the threads though the engine. Don't know which would be worse. Pulling the carbon through the spark plug threads or having it dump on the piston when it scrapes off (if the plug sticks out that much.

Though techron at regular intervals should minimize buildup on the plugs.

Alan

[KLS]

Alan,
I wasn't thinking of carbon flecks as a problem. I was thinking of the spark plug firmly glued into place by the carbon in the threads. Will the aluminum threads in the head strip out? It's very possible. I doubt if any additive could clean anything out of the threads. Maybe off the exposed surfaces, but not up inside the threads.

Ken

[akauth]

Originally posted by KLS
Alan,
I wasn't thinking of carbon flecks as a problem. I was thinking of the spark plug firmly glued into place by the carbon in the threads. Will the aluminum threads in the head strip out? It's very possible. I doubt if any additive could clean anything out of the threads. Maybe off the exposed surfaces, but not up inside the threads.

Ken

No, you're right nothing is going to clean the threads.

I always used an anti-seize so I've never found this to be an issue. The carbon buildup stops on the exposed surface and the anti seize does it's job. It's thick enough that nothing migrates. Usually when I change plugs the threads are as shiny as when they are "brand new". Maybe even more so as anti-seize is pretty reflective in itself. Wipe it off and it's new metal underneath.

I usually put anti-seize on everything. Even including lug nuts (which, admittedly, may be idiotic) but then I regularly check the torque on my lug nuts to make sure nothing is coming loose. Already someone broke a stud *loosening* a lug nut rotating tires so I broke down and put lubricant on all the studs to make sure it doesn't happen again - even though it is a new vehicle. I was too lazy to do it and really didn't think it was necessary. (And it shouldn't be.) But now I won't have to worry. I think those studs might be a little more susceptible to breaking, too, for some reason based on some of the posts here.

Now if you never put anti-seize on a plug (which I don't think is wise) you definitely have a point. Those plugs are going to be locked in. The only downside to putting anti-seize on is that if the area around the hole is dirty because you didn't blow it out, you can more easily pick up grit on the threads and then try to screw it in.

I've done that in the past, that's why I always blow it out now even it it "should" be clean. It's cheap insurance to make sure nothing falls in. I don't know what's there unless I blow it out. Then I know what is there - nothing. Even being covered on the Tundra, I don't know what might have fallen in there while it was on the assembly line. Better safe than sorry. Taking 5 extra minutes can save 30 hours of [needless] work (and expense).

I've never seen 100,000 miles on a plug so I don't know what it would look like. But if it's 3 times what's on my 30,000 mile plugs, that's 3 times nothing if you have anti-seize on the threads.

But I never did think about what might be on the tip. That's a good point. (Even if it wasn't what you were thinking). I think a bigger deal would be heat expansion and the migration of material from one surface to another so in a way you're getting a "weld" or rather a "meld" of materials. That's why I put anti-sieze on to stop that entirely. Along with oxidation of threads.

Alan

[alexcue]

Originally posted by nhparrot
I installed the Denso Iridium's at 30K, is running smoother now, but I would expect that after a plug change. The true test will be time.

Tyson,
There is "how-to" with diagrams and torque specs for changing plugs posted in the "Garage" forum.

I was re-reading some of the old Iridium Spark Plug threads. Just wondering, is the mileage and smoothness still around after several more thousand miles?

[TruthSeeker]

I just replaced my spark plugs at 102K miles. I bought my 2002 Tundra used, so I didn't know what the service history was. I found the original spark plugs in the engine. They were toast. The wires on two of them were very worn.

I went with the NGK Iridium plugs. The engine seems much smoother now. The only recommendations (besides the plugs) would be to make sure the engine is completely cold. It is an aluminum block and you can mess up the threads even with a little heat. Better be safe than sorry. Also, use anti-seize. The iridiums are supposed to be longer lasting and you wouldn't want any problems down the road (although my orignal plugs came out *fairly* easily). Once again, better be safe than sorry.

[ddvk]

I think changing plugs before 80K miles is a waste of money. If the recommendation is 100K, they do last 100K miles, changing them at 80K is a good PM measure -- but anything before that is a waste.