OEM is NGK Iridium spark plugs, with a recommended change interval of 60K miles. Every other Japanese car I have seen using NGK Iridiums has a change interval of 100-120K. Subaru seems to be overly conservative with the maintenance recommendations (e.g OCI of 6K with 0w-20 Idemitsu full synthetic on a non-turbo engine). Is changing the plugs at 60K just a waste?
Subaru 2.5L Iridium spark plug life only 60K?
- Thread starter NO2
- Start date
- Status
I owned a 07' WRX. I changed the plugs at 61972 miles. This is an old post of mine and why you might wanna change them:
https://forums.nasioc.com/forums/showthread.php?t=1884132
https://forums.nasioc.com/forums/showthread.php?t=1884132
The OE plugs will probably last 100k with no problems
Besides, replacing them is probably difficult on that engine. You can safely wait until you have to replace the head gaskets to change the plugs
Besides, replacing them is probably difficult on that engine. You can safely wait until you have to replace the head gaskets to change the plugs
Originally Posted By: NO2
OEM is NGK Iridium spark plugs, with a recommended change interval of 60K miles. Every other Japanese car I have seen using NGK Iridiums has a change interval of 100-120K. Subaru seems to be overly conservative with the maintenance recommendations (e.g OCI of 6K with 0w-20 Idemitsu full synthetic on a non-turbo engine). Is changing the plugs at 60K just a waste?
I would say "No" I have noticed a slight degradation in idle and performance in my previous 2012 Subaru Legacy with the 4 cylinder @57,000 miles. I had done all the homework about changing the plugs-it's not that hard-but I checked two dealers and they both wanted about $300.00 to change them out. So-I was going to do it myself. Look on youtube for directions.
Ended up getting rid of the car for various reasons. Maybe mine was built on a Friday or something
but we found the quality of the car to be at best mediocre. So we traded it in and got a solid high Blue Book for it. It was the best I could ask for.
OEM is NGK Iridium spark plugs, with a recommended change interval of 60K miles. Every other Japanese car I have seen using NGK Iridiums has a change interval of 100-120K. Subaru seems to be overly conservative with the maintenance recommendations (e.g OCI of 6K with 0w-20 Idemitsu full synthetic on a non-turbo engine). Is changing the plugs at 60K just a waste?
I would say "No" I have noticed a slight degradation in idle and performance in my previous 2012 Subaru Legacy with the 4 cylinder @57,000 miles. I had done all the homework about changing the plugs-it's not that hard-but I checked two dealers and they both wanted about $300.00 to change them out. So-I was going to do it myself. Look on youtube for directions.
Ended up getting rid of the car for various reasons. Maybe mine was built on a Friday or something
I would go by the recommendation because they're undoubtedly referencing the shorter interval for a reason. Personally, in the four cars I've had since 2003 ( when I bought the first one that came with iridiums ) I've never had them last to 100K miles without a noticeable degradation in performance. It's safe to say that I wanted to replace them much more than try to get 100K miles out of them...so being conservative may not have anything to do with it if ( for example ) it's even more noticeable on the 2.5 Subaru and has noted consequences.
I typically notice a drop in performance by 70K miles so my feeling is that they'll likely last to 100K miles or more but you...or your vehicle might not like that scenario. YMMV.
I typically notice a drop in performance by 70K miles so my feeling is that they'll likely last to 100K miles or more but you...or your vehicle might not like that scenario. YMMV.
Unique engine topology, do what Subaru says, or install a non-Subaru / Porsche / Volkswagen horizontally opposed motor and go 100K. Your choice.
Iridium / Platinum plugs, to quote my mechanic / machinist, "work great as long as they last" and then they fall off or fail abruptly.
Iridium / Platinum plugs, to quote my mechanic / machinist, "work great as long as they last" and then they fall off or fail abruptly.
Subaru boxers aren't too bad to replace plugs on - you might need to pull the intake ducting and/or the battery. It's like replacing plugs on any truck-based American SUV. Older Subies use waste-spark ignition and their wire boots are flexible to guide them out of the plug tubes.
I'd trust the OEM plugs to hit the 100K mark. If you use a "performance" single-tipped Ir/Pt plug, that figure will be much less.
I'd trust the OEM plugs to hit the 100K mark. If you use a "performance" single-tipped Ir/Pt plug, that figure will be much less.
If it's burning oil, than yes, they need to be changed.
Otherwise, probably not but then maybe their engineers know something we don't.
Otherwise, probably not but then maybe their engineers know something we don't.
The Subaru only is only burning 1Q every 7000 miles since I switched to M1 EP 0w-20, and almost all the miles are highway. We decided to go to 13-15K OCI since the warranty is up. I sort if get the performance issues, it happened on our Honda 3.0 V6 around 110K with Iridium plugs and occasional rough idling, but that could have been the timing belt stretching too (or even bad gas) .
Last edited:
I changed plugs on the wife's 14 Forester at 60k per the maintenance schedule. Engine was still running nice and smooth. They didn't look very worn at all, and didn't run any different after replacement.
They very well may have made it to 100k since it uses less than a quart of oil in between 7k mi OCIs.
They very well may have made it to 100k since it uses less than a quart of oil in between 7k mi OCIs.
4 cylinder non-turbo Subaru's are easy to change the spark plugs on. Check out guides on youtube and they'll show you exactly what needs to be done.
Also, get this: https://www.amazon.com/GearWrench-80546-8-Inch-6-Inch-Swivel/dp/B0014ZVSVK I got mine from the local AdvanceAuto for less than the cost on Amazon, and the fact that it gave added length, swiveled, and was magnetic made the job easier than if I didn't have it
Also, get this: https://www.amazon.com/GearWrench-80546-8-Inch-6-Inch-Swivel/dp/B0014ZVSVK I got mine from the local AdvanceAuto for less than the cost on Amazon, and the fact that it gave added length, swiveled, and was magnetic made the job easier than if I didn't have it
What do they use for an ignition system? Just a regular spark per cycle? Ford uses a waste fire system on some of their engines so they end up firing twice per cycle. Mercedes has a multi spark system on their direct injection engines so it fires up to 4 times per cycle which is why they recommend replacement every 60k.
- Status
