Bosch HR6DS spark plugs - went obsolete in 2019 with no replacement

[Chris 16409]

I have been stock piling the Bosch Silver plugs for this very reason. You can sometimes find them listed on eBay. Make a saved search so you can check regularly.

[David T]

When the iridium plugs first came out a few of us were using them. We started noticing the cars developed a miss, it was the plugs leaking at the seal. Went back to the regular plugs and never had a problem. The iridium plugs were developed so you could go 100,000 miles without touching the plugs. Not so important for most of us. Especially with their premium price! On boosted cars you should use a smaller gap. Experiment to find the best one.

[82DMC12]

Well I think I will try the NGK 2238 plugs. Easy to get at Autozone. I picked up a set tonight and checked the service book - it says to gap to .024 - .028. I know the plugs will wear down after many many miles but most of us don't put that kind of mileage on our cars. The Bosch HR6 plugs I pulled out were gapped to around .026. Should I set the NGK's to .026 as well? Right in the middle.

[dmcman73]

Thanks for the tip. They are available locally, too, if this the plug you are talking about?
https://shop.advanceautoparts.com/p/...238/19650088-p

Yes, those are the ones, but, you can get them for like a $1.50 each on Rockauto.

[dmcman73]

When the iridium plugs first came out a few of us were using them. We started noticing the cars developed a miss, it was the plugs leaking at the seal. Went back to the regular plugs and never had a problem. The iridium plugs were developed so you could go 100,000 miles without touching the plugs. Not so important for most of us. Especially with their premium price! On boosted cars you should use a smaller gap. Experiment to find the best one.

Are you talking about the Autolite iridiums? That's similar to what I am seeing as well, sort of a miss/backfire which is why I want to try the plain old NGK 2238's.

[FABombjoy]

When the iridium plugs first came out a few of us were using them. We started noticing the cars developed a miss, it was the plugs leaking at the seal.

Which plugs?
Which seal? The taper seal @ the heads or the weather seal?

There are advantages to iridium beyond wear properties. It sounds like something unrelated to the electrode is the issue.

On boosted cars you should use a smaller gap. Experiment to find the best one.

I'm not sure who the audience is here but I'll turn and address them too:
The IT22 is one-step colder than the IT20, gapped at 0.8mm (vs 1.1mm for the IT20) and works well on my low-boost turbo car. Wires are Magnecor.

[David T]

The ceramic to the outer shell leaked. Like they weren't crimped on properly. Very unusual, never saw that on any other plug. Had to be a manufacturing defect. Usually one out of 6. Very easy to see once you pull the plugs, you can see the residue stain on the ceramic. No one saw any benefits from using them, especially at the price at the time, so we went back to the standard plugs. It's the same the ignition coils, air filters (K & N), and the ignition wires. Some owners bought "performance" parts and either did not see any improvement or worse, the parts fail prematurely.

[dmcman73]

The ceramic to the outer shell leaked. Like they weren't crimped on properly. Very unusual, never saw that on any other plug. Had to be a manufacturing defect. Usually one out of 6. Very easy to see once you pull the plugs, you can see the residue stain on the ceramic. No one saw any benefits from using them, especially at the price at the time, so we went back to the standard plugs. It's the same the ignition coils, air filters (K & N), and the ignition wires. Some owners bought "performance" parts and either did not see any improvement or worse, the parts fail prematurely.

The market is flooded with counterfeit parts, including spark plugs. Depending where they bought their plugs from (like Amazon, eBay, etc), the units with leaking ceramics could have been knock offs and some of the knock offs look like the real thing minus some subtle differences.

[David T]

You're right, it could have been knock-offs but they were bought through reputable distributors. The other possibility is that Bosch started "outsourcing", getting their stuff made in 3rd world countries, and the quality went downhill. In any case they were not worth the premium price. Maybe now they are better? Still, what benefits do Iridium plugs offer besides a longer service interval which is irrelevant to most of us.

[DL4567]

dmcman73, did you install the NGK 2238s? How do you like them?
I'm trying to figure out which ones to buy for my car, or even whether to replace them all all. I'm in the valley for another reason, and figured I'd do plugs, wires, distributor cap and rotor, and fuel lines while I'm in there. (all new experiences for me -- I'm no expert).