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Discussion Starter #1
Is there a conclusion as to which is the better plug for the LT, the OEM Bosch XR7LDC or the NGK DCPR7EIX Iridium? Do they actually perform better with the Iridium, or is it all marketing, and does someone have some hard evidence to back up the claims?
 

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Well I ran the stock to 12, then used Iridum, and now just changed back to OEM Bosch duels. My iridum were worn and while I did not check the gaps, they looked big and the iridum worn.

I noticed no difference between the two performance or mileage wise.
 

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I believe the iridium is superior simply because I can run them for about 50,000 miles.


Just my $.02.
 

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Discussion Starter #4
I never heard of anybody running plugs for 50,000 miles. While they might still work, I would suspect the performance would not be as good.
 

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No noticable difference in performance or mileage. I think my first set of platinums I ran about 30,000, then I tried the iridium and I'm sold.
 

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tonyn1 said:
I never heard of anybody running plugs for 50,000 miles. While they might still work, I would suspect the performance would not be as good.
On my cars I do - as a matter of fact, I'm just getting ready to change a set on wife's Audi after 105k. (And before you flame me: I do have nice cars and I do keep them a very long time.)

I am not sure how you'd judge fall-off in performance, but I have not experienced poor starting or driveability, nor decrease in fuel economy.

On the bike, I change more often simply because I like to play with the machine.
 

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rdwalker said:
On my cars I do - as a matter of fact, I'm just getting ready to change a set on wife's Audi after 105k. (And before you flame me: I do have nice cars and I do keep them a very long time.)
+1

Not to hijack the thread, but the owners manual on my BMW 3-series car says change those plugs every 100K miles. I did mine (OEM replacement) also around the 105K to 110K range - only because I figured it would be interesting to do it myself (easy on this car) and see if anything improved. I'm guessing it made a difference... however it was smooth running before/after, pretty much identical MPG too. And will not worry about for a while as well.

So back to the LT, I figure I'll replace my plugs when I see a change in driveability/MPG/starting, etc. Have 25K on my 05 and really not considering doing a change anytime soon. It's running great! (FYI - I do change the oil, etc. regularly) And since I got the same OEM plugs, I'll put those in too. maybe the LT is easy on plugs?

Jon
 

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In my experience if you run them too long the gap gets too large and the voltage needed to jump the gap goes up and that puts undue voltage pressure on the coil packs secondary side . You juggle the $ coil pack verses spark plugs .
 

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gbob said:
... if you run them too long the gap gets too large ...
This past off-season, I changed the plugs on the LT, at about 40k miles. The old ones were very likely original (I'm the second owner, thus cannot be certain).

Being anal (yes, I am...), I compared the old ones to the new set. The gap was within the tolerance of the feeler gauge - almost identical.
 

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I get the 24K kit from Beemerboneyard and change everything at 12K miles. The plugs always look good but I got new ones to put in so...I do.
 

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LAF said:
Well I ran the stock to 12, then used Iridum, and now just changed back to OEM Bosch duels. My iridum were worn and while I did not check the gaps, they looked big and the iridum worn.

I noticed no difference between the two performance or mileage wise.
same for me, OEM first set went in @ 12K (WAY to soon IMO) next @ 45K, very little diff in look or performance. Highway verses city driving make a HUGE difference, less plug life on City driving- stop & go.
 
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