NGK Iridium Spark Plug is very nice product. My Subaru had been running a little rough and it was time for new spark plugs so I decided to go for the upgrade and try iridium plugs. The old plugs had about 50k miles on them and were long overdue for replacement. The OEM plugs were platinum and I had been told that platinum plugs can last as long as 100k miles. That certainly wasn’t the case here as after 50k they were all fouled.
I installed the new iridium plugs and suddenly my engine was like new again! The idle was quiet and smooth like it should be. I’ve also noticed a slight increase in fuel economy, but that’s no surprise after replacing fouled out plugs. Having only put about 1k miles on them so far I can’t say whether the BKR5EIX-11 Iridium IX Spark Plugs are any better than the OEM platinum plugs, but they’re about the same price so why not give them a try? Iridium is a much harder metal than platinum, with a substantially higher melting point, so these plugs are more durable and should last longer than platinum at least in theory.
They don’t run any hotter than the OEM plugs, but with a finer electrode they require less power to generate a spark, which means they’re more efficient. I expected them to be pre-gapped, but since they’re not the OEM plugs for my Impreza 2.5i they weren’t gapped correctly for my car. I don’t know if it’s because iridium is a much harder metal than platinum and copper, or just that my hands aren’t as strong as they used to be, but I really had a tough time setting the proper gap of 0.44. Once I finally got them gapped I decided to save a lot of money and install them myself. I checked an online Subaru forum and some people said it was very difficult to change out the plugs on a 2008 Impreza.
While I wouldn’t say it was easy, I definitely would not say it was all that hard. As long as you have a standard 5/8” spark plug socket, a 3” or 4” extension, a swivel bit, and a little bit of patience, I don’t see any reason to pay a shop or dealership a ridiculous sum of money to install them for you. Perhaps if you consider your time extremely valuable or maybe you spent a lot on your manicure it would be worth it, but you don’t need to be a master mechanic to install new plugs in an Impreza. If you prefer to leave such tasks to the professionals, no judgement here. I’m just a little short on cash right now and the dealership wanted an awful lot of money to swap out four spark plugs.
