What's the latest news on PLUGS for G37??? We have 125k miles on original plugs. Searches have led me to NGK 91784 Ruthenium. Who has actually used those on a stock G37? Any reviews?? Any actual experiences? Good? or Problem?

Reply quick please because I gotta make the purchase in a day or so in order to finish the swap before my wife needs car again for commuting to office as Covid rules loosen up....
So, Should I Ruthenium or not???
Also regarding spark plug gaps, I have read many times that some of the modern plug metallic platings are thin, so you really have to avoid aggressive re-gaping! Be careful.

 

Your searches have misled you.......OEM plugs Denso 3457, nothing else.

 

I also recommend strictly using OEM plugs. That’s how the manufacturers intended the vehicle to run optimally.

 

Strongly agree. Only use OEM Plugs

NGK PLFR 5A-11 from my previous 06 G35 6 speed replaced at 106k miles



I should have thrown these out 10 years ago

 

As to the drops of coolant you're seeing check the coolant lines going to the throttle bodies for leaks.

 

Thanks. Yep, I've read about original spec which is likely Denso, but I also see people mention using/finding NGK as OEM, correct??....

The Denso especially seem sold out / not-available at many places, and I'm also concerned about getting stuck with counterfeit versions if I do web mail order!

I know there's an OEM rule of thumb, I'm really surprised no-one has any specific experience using 2009 G37 Sedan sparkplugs that might be cross-referenced by various sites... Specifically Autolite versions, Rutherium, etc.... Maybe a newer Denso? Anyone?
Any help would be appreciated. 2009 G37 Sedan has 125k miles on it, but runs great, so I guess I can just wait til I find some actual G37 reviews using other sparkplugs... I'm also thinking about removing/inspecting a couple of the easier plugs to reach so I can confirm what's installed (factory) and the condition of our electrodes! Maybe if they look good I'll decide it can go another 20k miles!

 

Orig OEM removed at 122.2k miles.


I relented my pursuit of a more readily available and less expensive plug and simply ordered OEM DENSO from a reputable chain for pickup at local store. With magnifying glass I confirmed that electrode "tips" were welded-on,, hence legit iridium before leaving counter. The counter guys remarked that the 6 plugs were hard to find, so i think eventually alternatives may be necessary for some owners!!

Install went smoothly yesterday and I also sprayed and cleaned both throttle bodies. All 6 plug tubes were dry and clean.

At 122.2k miles and 11 years, our G37Journey sedan was still running fine on the original plugs.

Looking at overall condition and well-defined remaining tips of the plugs removed (pics) I think I would have put more mileage on them before replacement even though the ceramics look a bit charred... Car was running fine before, and wife reports it's running almost the same now with new plugs.

​​​​I obviously replaced them all yesterday because i was already in there and had the replacements in hand... For other owners maybe wait until MPG, idle quality or performance declines??

Can anybody decern anything further from these plugs? I think the pics are pretty clear.

 

Plugs should always be PM. If you til there a problem then it doesn't really help.

 

your old plugs still look good. Looks like your motor is extremely healthy. When I did my plugs at 130k there was a **** ton of oil in the tubes so I re Did my valve cover gasket and spark plug tube seals. I’m gonna be replacing the plugs again when I supercharge so we’ll see if they’re nice and clean then.

 

OK, so based on replies, it seems my 2009 G37 sparkplug replacement last weekend at 122.2k miles was good for PM (preventative maintenance), and the decent condition of the removed plugs (pics) indicate very good engine health. Thanks! So, I'd say it was a win-win.

I do think the DENSO OEM plug is getting harder to find and is more expensive already (and also "faked now" I think), so eventually more people will have to buy and report on alternatives. If the Autolite Iridium had been widely & positively reported on G's I would have gladly bought those instead for half the price. We won't likely keep the car another 100k miles (next sparkplug change) so I guess I'll never know. Best wishes to all G's!

 

I’ve been using Ruthenium plugs for thousands of miles now without any issues at all. I drive my M37 very spirited every day. Anyone that says “stick with stock” still has paper filters and uses the factory fluids. Obviously these commenters aren’t very intelligent.

 

Kicking a dead horse bud