Factory spark plugs

Hi all,

 

I have a 2007 JDM 2.0T BL5 B spec Legacy.

 

Last year I called my local Subaru specialists in Christchurch, New Zealand asking for a quote to change my spark plugs. They asked me what model car I had so I let them know and they told me that the factory spark plugs found in this car last an age and can last 200k+ kms. They say that they've pulled out clean spark plugs on several occasions from BL5 Legacys that their owners state they have never changed their spark plugs during their ownership.

 

Now, I am quite skeptical about this but I've left it until now, but I thought I may as well ask the question.

 

Has anyone had any previous experience with their spark plugs, or can anyone please debunk this theory.

 

In the case that this is false, are Iridium plugs the way to go?

No input on the Spec B part but I recently changed the plugs in my '09 LGT with 55k miles. While the plugs taken out didn't look bad, I feel better having done them so I know how and that they are new. I went with the factory plugs - some fancy Laser Iridium NGK's. I would not wait until 200k km's as the plugs may not come out without a real battle at that point. Even if the plug still works you want to change them before you pull the threads out of the head or break the plugs off due to corrosion. How many miles/km's on the car?

Can’t say much about the JDM engine but the USDM owners manual states 60k miles or 100k kilometers. Copper is a better conductor. Iridium is generally fine and is typically used anyways because it lasts twice as long. I wouldn’t run double that recommended mileage on copper plugs, which is more than likely what you have right now.

 

Also considering how much of a pain it is sometimes to replace without loosening the engine mounts, I personally would rather use the plug that lasts the longest.

No input on the Spec B part but I recently changed the plugs in my '09 LGT with 55k miles. While the plugs taken out didn't look bad, I feel better having done them so I know how and that they are new. I went with the factory plugs - some fancy Laser Iridium NGK's. I would not wait until 200k km's as the plugs may not come out without a real battle at that point. Even if the plug still works you want to change them before you pull the threads out of the head or break the plugs off due to corrosion. How many miles/km's on the car?

 

Forgot to mention, probably the most important piece of information! Currently at 155k kms and have owned for about 16k kms. I have never changed the plugs and don't know if they have been changed previously either.

That is incorrect.

 

The factory plugs will be double Platinum and they are good for 100,000Km.

 

I have changed some at 120,000Km but they are stuffed. The tiny platinum "Puck" on the ground electrode has gone and its getting blasted opening up your plug gap.

 

Changing the plugs on these cars is a pain in the ass, the 6 Cylinder is even worse. it took me like 2 hours to change the plugs so use Platinum.

 

Platinum plugs from the dealers here in New Zealand are like $45 each, just a major rippoff so I get mine out of the USA for like USD$12 each.

That is incorrect.

 

The factory plugs will be double Platinum and they are good for 100,000Km.

 

I have changed some at 120,000Km but they are stuffed. The tiny platinum "Puck" on the ground electrode has gone and its getting blasted opening up your plug gap.

 

Changing the plugs on these cars is a pain in the ass, the 6 Cylinder is even worse. it took me like 2 hours to change the plugs so use Platinum.

 

Platinum plugs from the dealers here in New Zealand are like $45 each, just a major rippoff so I get mine out of the USA for like USD$12 each.

 

I have some supercheapauto credits so leaning towards getting some NGK iridium plugs. Is there much difference between iridium and platinum other than longevity of use?

No difference, just the Platinum ones are specified to last longer.

 

The Iridium ones are cheaper. Its just that its not a 10 minute job to change them in a Subaru like it is my Toyota so its a job you really only want to do once.

I just changed my plugs on saturday, 80,000kms and they definitely needed changing. I was starting to get an occasional misfire code come up. I haven't had one since, so I think I'm all good.

 

I found the easiest way to change plugs on these subaru's is to pull the battery on the drivers side and the airbox on the passenger side, at that point it was simple with a swivel joint on my spark plug socket and a decent 3/8" extension. Took just over an hour then

 

Forgot to mention, the new plugs were from the dealership, NGK Iridiums

Even if spark plugs can last a long time these days they slowly deteriorate and it leads to performance impacts caused by random misfires at high power conditions, but it can also give occasional misfires when idling.