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

[82DMC12]

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).

You're probably actually asking me, not dmcman73 since I started the thread. Yes I installed the NGK 2238's, I gapped them right in the middle of the recommended range, and put a dab of antiseize on the threads with a brush before installing. I probably only put 50 miles on them before starting a new project where the car is laid up for a while but they seemed to work just fine. Based on that and other's experience I'd say they are a good buy.

[DL4567]

You're probably actually asking me, not dmcman73 since I started the thread. Yes I installed the NGK 2238's, I gapped them right in the middle of the recommended range, and put a dab of antiseize on the threads with a brush before installing. I probably only put 50 miles on them before starting a new project where the car is laid up for a while but they seemed to work just fine. Based on that and other's experience I'd say they are a good buy.

Thanks! I've never changed spark plugs before on any engine, so trying to figure out if it's even necessary at this point. To my knowledge, they were fresh 14,000 miles / 21 years ago. (28k-42k miles)

[82DMC12]

Thanks! I've never changed spark plugs before on any engine, so trying to figure out if it's even necessary at this point. To my knowledge, they were fresh 14,000 miles / 21 years ago. (28k-42k miles)

Well if they have been in there for over 20 years I'd definitely recommend pulling them out. You don't want them to seize up in the engine. Plus, checking your plugs tells you a lot about the health of your engine. You should probably get the engine nice and hot and pull them out while the engine is still hot to the touch. If you try to take them out cold you might find them hard to remove (even worse, break one off). Maybe put a couple drops of marvel mystery oil into the plug wells a couple days prior first to help yourself out.

[Mark D]

You should probably get the engine nice and hot and pull them out while the engine is still hot to the touch.

Pulling spark plugs from an aluminum head when it's still hot can increase the likelihood of stripping the threads out of the head. Warm is OK, but everything I've read says not to pull plugs when the engine is still hot.

Seems to be true for installation as well in terms of stripping threads. A hot engine can also affect the residual torque value on the plugs.

[DL4567]

If I pull them, it's going to be stone cold, as I've had the intake manifold and all other necessary parts off the engine for some time.