Spark plugs for 99 OBW

[Rooster2]

What brand spark plugs and model # recommended for my 99 OBW. I just threw a code, and #4 has a mis-fire, so prolly plugs going bad. If new plugs don't fix, then I will install wires. Thanks for any recommendations.

 

I tried using the search feature here, but could not get it to work.

Edited June 1, 2015 by Rooster2

[Dinky26]

NGK brand are the best brand, model # will depend on the engine 2.2 or 2.5.

 

In my opinion I would change the wires at the same time while you are there.

I have done them individually and it's not worth the hassel of going back again.

Not to mention if one part isn't that good the other is probably on the way out, just a good maintence thing to do.

[Rooster2]

NGK brand are the best brand, model # will depend on the engine 2.2 or 2.5.

 

In my opinion I would change the wires at the same time while you are there.

I have done them individually and it's not worth the hassel of going back again.

Not to mention if one part isn't that good the other is probably on the way out, just a good maintence thing to do.

Good thought about changing all the spark plug wires, I was thinking the same thing.

 

I am thinking that NKG Iridium BKR5E-IX  is a good plug choice.

[Dinky26]

There is great debate on the efficacy of the expensive plugs being worthwhile. 

 

I prefer to go with the base price plug.

[Rooster2]

There is great debate on the efficacy of the expensive plugs being worthwhile. 

 

I prefer to go with the base price plug.

I have Bosch Platinum plugs in the car now. The one with just a single anode. They have about 40K miles on them, so not surprised that one plug is starting to misfire. The Bosch plugs have been fine, but didn't expect them to last forever.

 

Since plug swap is such a wrenching hassle with the 2.5 motor, I figured I would go to the more expensive NKG Iridium plugs, hoping for more then 40K miles in the future.

[Dinky26]

Not really sure what the average mileage life of the NGKs are, depends on several factors.

[keith3267]

There is a long discussion  about spark plugs on this thread, which is on this page by the way.

 

http://www.ultimatesubaru.org/forum/topic/150167-question-about-spark-plugs/

 

I would not recommend replacing the spark plug wires unless the boots are hard and cracked.  The early carbon filled resistor cables of the 60"s got a bad reputation for not lasting very long.  They were usually good until you changed the plugs, then the flexing of the wires would cause them to leak and misfire so it was not uncommon the change the cables with the plugs, or with every other plug change anyway.  Plug changes back then were usually every 12k miles.

 

Todays cables are make with a kevlar reinforced carbon conductor.  The kevlar holds the carbon in place.  The cables are covered with silicone rubber. they do not leak.  The only weak part is the rubber boots at each end.  As long as they are pliable and not cracked, they are good.  It helps to keep them coated with a good silicone dielectric grease.  If the boots get hard and cracked, they have to be replaced, and since they are molded to the cables, the whole cable must be replaced.  I have had several cars go 200 to 300k miles on the OEM cables and never miss a beat.  But I do coat the boots with silicone dielectric grease when ever I change the plugs, which isn't very often because I use double platinum or iridium/platinum plugs.

 

If the ground strap of the plug does not have a platinum pad on it, then it will erode faster than one that has the pad.  The ground straps with the pad last almost forever.

 

Because platinum and iridium is a much harder material, it does not erode nearly as quickly as an iron tip.  The harder material can be made into a smaller/finer point and still last a very long time. The finer point concentrates the corona around the tip.  The corona is the ionization of the gasses around the tip and the smaller the corona, the less voltage it takes to create an arc (spark) and the more intense and hotter the spark will be.  This is of value only if the fuel air mix in the combustion chamber is not close to ideal. Once the fuel is ignited, the spark is of little consequence.  It does not matter how hot or intense it was.  Its just that a hotter or more intense spark is more reliable in igniting the fuel in less than ideal conditions and this is another reason the plugs can remain in the engine for a much longer time.

 

If you use NGK or Denso plugs, they have an anti-seize plating on them.  They do not need and you should not use an anti-seize grease on the threads.  Other brands may or may not have the plating so you will need to use the anti-seize compound on the threads.  I have never had an issue with removing the plated NGK or Denso plugs even after 120k miles.

[Rooster2]

There is a long discussion  about spark plugs on this thread, which is on this page by the way.

 

http://www.ultimatesubaru.org/forum/topic/150167-question-about-spark-plugs/

 

I would not recommend replacing the spark plug wires unless the boots are hard and cracked.  The early carbon filled resistor cables of the 60"s got a bad reputation for not lasting very long.  They were usually good until you changed the plugs, then the flexing of the wires would cause them to leak and misfire so it was not uncommon the change the cables with the plugs, or with every other plug change anyway.  Plug changes back then were usually every 12k miles.

 

Todays cables are make with a kevlar reinforced carbon conductor.  The kevlar holds the carbon in place.  The cables are covered with silicone rubber. they do not leak.  The only weak part is the rubber boots at each end.  As long as they are pliable and not cracked, they are good.  It helps to keep them coated with a good silicone dielectric grease.  If the boots get hard and cracked, they have to be replaced, and since they are molded to the cables, the whole cable must be replaced.  I have had several cars go 200 to 300k miles on the OEM cables and never miss a beat.  But I do coat the boots with silicone dielectric grease when ever I change the plugs, which isn't very often because I use double platinum or iridium/platinum plugs.

 

If the ground strap of the plug does not have a platinum pad on it, then it will erode faster than one that has the pad.  The ground straps with the pad last almost forever.

 

Because platinum and iridium is a much harder material, it does not erode nearly as quickly as an iron tip.  The harder material can be made into a smaller/finer point and still last a very long time. The finer point concentrates the corona around the tip.  The corona is the ionization of the gasses around the tip and the smaller the corona, the less voltage it takes to create an arc (spark) and the more intense and hotter the spark will be.  This is of value only if the fuel air mix in the combustion chamber is not close to ideal. Once the fuel is ignited, the spark is of little consequence.  It does not matter how hot or intense it was.  Its just that a hotter or more intense spark is more reliable in igniting the fuel in less than ideal conditions and this is another reason the plugs can remain in the engine for a much longer time.

 

If you use NGK or Denso plugs, they have an anti-seize plating on them.  They do not need and you should not use an anti-seize grease on the threads.  Other brands may or may not have the plating so you will need to use the anti-seize compound on the threads.  I have never had an issue with removing the plated NGK or Denso plugs even after 120k miles.

Good write up. very educational...........Thanks,..............Rooster 2 (Larry)

[86 Wonder Wedge]

NGK Stock# 2300. NGK PFR5B11. Laser Platinums (double platinum). Yes, they are up there a bit, but do the job once with the proper plugs and you won't have an issue.

 

Subaru didn't spend lots of research dollars on a finding a good plug to use and decide on a double platinum plug "just because".

[Rooster2]

NGK Stock# 2300. NGK PFR5B11. Laser Platinums (double platinum). Yes, they are up there a bit, but do the job once with the proper plugs and you won't have an issue.

 

Subaru didn't spend lots of research dollars on a finding a good plug to use and decide on a double platinum plug "just because".

I ordered on line the NKG Iridium BKR5E-IX. So confusing on spark plug purchasing. So many models from so many manufactures. I am hoping that spending a few bucks more on plugs, buys longer milage life. Like everything, progress moves on, so hoping that the newer NKG plug offering is better then what Subaru recommended back in 99, when the car was new.