I bought new NGK plugs for my RDX. The box says they are 0.32 gap

The service manual says the plugs must be 0.28-0.31
Is it worth regapping them ? I don't think NGK's are iridium, so it should be safe

 

B

other NGK Laser Iridium and the Rutheniums are preset the the OE gap so you should be good without. Do you know which ones you got?

 

In the RDX manual I have it says not to regap Iridium plugs, just replace if out of spec and probably the same for Ruthenium but not sure if there were Ruthenium plugs available at the time the manual was written. Gap specified is 0.7mm-0.8mm (0.0276-0.0315 inch).

 

Not sure why the FSM says .7-.8 mm gap when it simultaneously lists the .032" pre-gapped, non-adjustable NGK SILKR8A-S as the OEM plug. I guess if you were to get platinum plugs instead, then you might re-gap them down to .030". But I'd say there is zero chance that the shop or dealer is re-gapping iridium plugs on these prior to install. FWIW, I'm on my third set, and have not had any issue with them.

Really, in a normal use case for this car you're not going to see a performance difference in a .001" gap variance. A shop sent me the wrong plugs once and I did not notice until after install, and even then the car ran fine on .044" plugs and only misfired a bit under throttle. But, it was enough to notice, and honestly if it didn't start doing that right after I changed plugs I could have easily mistaken the cause for something else.

TL;DR - throw in 4 OEM's as-is and you'll be good to go.

 

I bought NGK LKR8BHX-S (stock no 90465) which are pregapped to 0.032. But the manual says 0.0276-0.0315 inch (as DCS points out). So they are pregapped out of spec? (This is what RockAuto recommended for my vehicle)

These are "Ruthenium HX" plugs, and Ruthenium is in the platinum family.,..so not sure if it's even ok to regap these.

 

Sorry, to clarify, I'm not disagreeing with you. I have a copy of the '07 FSM and it lists both the recommended gap as well as the recommended plug, which is iridium and generally not meant to be adjusted from its preset gap. So, those two points kind of conflict with each other. But again, I'm 210k+ miles on oem plugs and the engine runs like a champ. I do not believe there is any risk in sticking with the oem plug at .032" gap. But if you do get plugs that can be re-gapped, then you have a recommend range to work with. At least, that is how I am interpreting it.

As far as ruthenium, that's a new term to me but from what I can see they, like iridium, should not be re-gapped.