Rossi

I am about to replace spark plugs again on my 2009 GTS.
I have been using BOSCHFGR5NQE04, (which I believe are copper plated right?)

I came across DENSO5345 are now available for my application.
- Denso is top-notch company, (I have been using them on my Lexus ISF)
- anyone upgraded to Iridium ones?
- any reason NOT to upgrade and just to stick with Bosch?
- any feedback would be greatly appreciated.

Rossi

https://www.carsdirect.com/car-repai...op-performance

Just read this, I guess copper is the best for performance, if not focusing on longevity. I am OK with that.

v10rick

After 30K mi I just replaced my plugs and found all the coils were cracked. 75K mi. on the clock.
Noticeable improvement with new plugs and coils.

Wondering what you will find when the plugs are replaced.

Petza914

Iridium and Platinum are only used for longevity. Copper is a better conductor than both with the only thing being better than that Silver, but you'll spend a fair amount of time trying to track down a silver plug with the right heat range, seat, reach, and gap (if multi-electrode). I sometimes spend the time to do this based on what plugs look like when I pull them from one of my modified motors. For example I'm lowering the plug heat range in my supercharged 997 based on the condition of the plug electrodes, but for a stock GTS, probably not much to be gained by reinstalling something other than the stock plug.

If you try the others, let us know how it goes.

Rossi

Thank you Rick.
I am definitely due to replace the coil packs this time around. I just replaced one recently, the remaining (7) are the original units, now at 148K.
Looking forward to it. After I replaced spark plug and coil pack (cylinder 8, got a CEL P0308), completely fixed my rough idle / idle drop at stop lights. Time to replace the rest for sure.

Thank you Petza.
I am sticking with Bosch units. There is a slight chance I might have gotten fake ones last time around as I was not aware of the counterfeit problems with eBay/Amazon sellers.
I noticed the new spark plug I purchased recently from PelicanParts had the blue print on the plug varying slightly from the one I replaced. So PelicanParts, here I go to get the rest of them. No more taking chances buying from unreliable sellers. With my car burning oil, no reason to try to extend the interval by getting Iridium units. I am inclined to replaced the plugs more frequently to make sure everything runs smooth.

v10rick

Rossi, I know you were searching for a cause, what is the latest? How much oil are you loosing?

Rossi

No major update unfortunately. I haven’t been driving that much with California being on the lockdown for sixth week. It got better with my second Amsoil oil change. I am at about a quart every 600. (Up from 400). Just replaced the both plastic AOS connector lines, as the diaphragm was done recently. I must say, the car has a noticeable better punch, hopefully I gain something from that.

Pillow

Denzo Iridiums here on an S. No problems at all.

100k change interval and Send It! Don't over think it as Iridiums are proven to work in all sorts of cars.